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Briggs 18.5 hp Wont Run

Mar 20, 2023#1

K

kkjfjns2014

Hello all, I have a 2006 briggs and stratton 18.5 HP [31N707] engine that came off a craftsman. We put it on a small ariens zero turn. It worked very well for awhile, then got it where it wouldn't run unless the choke was on. Eventually it quit running all together. After this my dad parked it and it sat for 2 years.

I decided to try and fix it for him this year. There was water in the gas, so I took that tank off and drained it and dried it in the sun for a few days. I put it back on put in fresh gas. I also replaced the carb and all fuel lines and vacuum lines and filters. I put the choke on and started it and it ran for about 10 seconds, I took the choke off and now it's back to not running at all again. Tried tinkering with the air/fuel mix a bit, still no luck. If you feed it gas directly into the carb it will run. It has good spark, everything else seems to be functioning, I have no idea what else to do. I'm about to pull my hair put. Any advice on next steps would be greatly appreciated. Thank you.

Mar 21, 2023#2

B

Bertrrr

Sounds like the fuel pump is not working, I keep a small electric fuel pump on hand to use when I run into an issue where I think the fuel pump is bad. You probably have the diaphram type pump and it has dry rotted over time.

Mar 21, 2023#3

I

ILENGINE

Or is this a case where the old Ariens engine had a fuel pump but the craftsman doesn't and it ran as long as the fuel level in the tank was above the carb allowing gravity flow into the carb. And when the fuel dropped to a certain level it no longer was getting into the carb.

Mar 21, 2023#4

K

kkjfjns2014

Bertrrr said:
Sounds like the fuel pump is not working, I keep a small electric fuel pump on hand to use when I run into an issue where I think the fuel pump is bad. You probably have the diaphram type pump and it has dry rotted over time.

I replaced the vaccum pump as well and verified fuel flow while cranking

Mar 21, 2023#5

K

kkjfjns2014

ILENGINE said:
Or is this a case where the old Ariens engine had a fuel pump but the craftsman doesn't and it ran as long as the fuel level in the tank was above the carb allowing gravity flow into the carb. And when the fuel dropped to a certain level it no longer was getting into the carb.

Think it's getting to much gas? Shouldn't the float in the carb stop it from getting to much gas?

Mar 21, 2023#6

B

Bertrrr

If it was getting too much gas it would be running out of the carb, the float may be stuck or is there a solenoid shut off under the bowl ? Post a few pics if you can

Mar 21, 2023#7

K

kkjfjns2014

Bertrrr said:
If it was getting too much gas it would be running out of the carb, the float may be stuck or is there a solenoid shut off under the bowl ? Post a few pics if you can

There is a solenoid shut off on the bottom, but I cut it off because the wire wasn't giving a reliable connection. I did notice it blowing some gas back and found out that means the valves may be out of whack. Do you know what the valve clearances on this engine are?

Mar 21, 2023#8

B

Bertrrr

That Solenoid needs 12volts to open and let fuel into the machine , if you cut the wire , there's your problem
Also the Solenoid keeps it from backfiring when you kill the ignition
If you have compression and it runs , doubtful you have a valve clearance issue

Mar 22, 2023#9

smhardesty

Bertrrr said:
That Solenoid needs 12volts to open and let fuel into the machine , if you cut the wire , there's your problem
Also the Solenoid keeps it from backfiring when you kill the ignition
If you have compression and it runs , doubtful you have a valve clearance issue

Yep. Cutting the wire was the wrong thing to do. If you don't want to replace a somewhat costly solenoid, remove the bowl with the solenoid still attached, pull the plunger up and cut it off. That's a poor man's fix for that solenoid. Not exactly the type of repair that is recommended, but it will solve the problem of a bad solenoid shutting the fuel off to the carb.

Mar 22, 2023#10

StarTech

And then this is done and the engine come into my shop it gets a new solenoid and customer gets the bill for being stupid. Sorry but is how I feel about it but it is one stupid thing that can fixed. Other stupid things can't be fixed.

Oh btw those fuel solenoids are cleanable.

Mar 22, 2023#11

smhardesty

StarTech said:
And then this is done and the engine come into my shop it gets a new solenoid and customer gets the bill for being stupid. Sorry but is how I feel about it but it is one stupid thing that can fixed. Other stupid things can't be fixed.

Oh btw those fuel solenoids are cleanable.

I specified it was a poor man's fix and clearly stated it wasn't the recommended way to fix it. He had stated he already cut the wire off the solenoid to try and fix his fuel flow problem. I was simply offering what I'll call the correct way to do a poor man's repair job and a brief explanation that cutting the wire wasn't going to solve a sticking solenoid plunger. No, I wouldn't recommend that to everyone, but it will solve his problem on the cheap, whereas cutting the wire had the reverse affect on the plunger.

Mar 22, 2023#12

B

bertsmobile1

kkjfjns2014 said:
There is a solenoid shut off on the bottom, but I cut it off because the wire wasn't giving a reliable connection. I did notice it blowing some gas back and found out that means the valves may be out of whack. Do you know what the valve clearances on this engine are?

0.004" both sides

Mar 22, 2023#13

K

kkjfjns2014

Bertrrr said:
If it was getting too much gas it would be running out of the carb, the float may be stuck or is there a solenoid shut off under the bowl ? Post a few pics if you can

StarTech said:
And then this is done and the engine come into my shop it gets a new solenoid and customer gets the bill for being stupid. Sorry but is how I feel about it but it is one stupid thing that can fixed. Other stupid things can't be fixed.

Oh btw those fuel solenoids are cleanable.

I didn't cut the wire I cut the plunger on it, I'm not a total idiot lol.

Mar 22, 2023#14

K

kkjfjns2014

bertsmobile1 said:
0.004" both sides

Thank you for answering my actual question instead of judging me

Mar 22, 2023#15

K

kkjfjns2014

Bertrrr said:
That Solenoid needs 12volts to open and let fuel into the machine , if you cut the wire , there's your problem
Also the Solenoid keeps it from backfiring when you kill the ignition
If you have compression and it runs , doubtful you have a valve clearance issue

I cut the plunger on it not the wire.

Mar 22, 2023#16

K

kkjfjns2014

Bertrrr said:
That Solenoid needs 12volts to open and let fuel into the machine , if you cut the wire , there's your problem
Also the Solenoid keeps it from backfiring when you kill the ignition
If you have compression and it runs , doubtful you have a valve clearance issue

It would only run with the choke on and I noticed it blowing some gas back out of the carb last time I tried starting it. Local mower man suggested valve adjustment as the next step.

Mar 22, 2023#17

K

kkjfjns2014

kkjfjns2014 said:
I cut the plunger on it not the wire.

Sorry everyone I realize how I worded that made it seem like I cut the wire and not the plunger on the end of the Solenoid. I just did it because no matter how I tried to put the wire in and get it tight I could hear it clicking up and down every time you barely touch the wire so I imagine as you're bouncing through the yard it would probably be cutting the gas off intermittently. I'm going to check the valves tonight and report back what I find. Thank you all for your help thus far.

Mar 22, 2023#18

K

kkjfjns2014

bertsmobile1 said:
0.004" both sides

These are the specs I found online for this specific engine model. Does it seem accurate? Or should I just roll with the .004?

Mar 23, 2023#19

F

Forest#2

.003 intake
.005 Ex

Intake is the main one to get set at .003-.005. go for .003 because the ACR (Automatic compression release) is on the intake cam lobe of the valve
BUT
You say the engine cranks fast which indicates that the valve lash may not be the main problem YET. (but can be easily checked)
You can see you tube videos of how to do such for your Model Briggs))

You say in post #7 when it's cranking fast you see gas blowing back up into the carb throat. seeing gas blowing back is normal on that Model engine when the engine does not start and it's getting too much gas into the carb float due to flooding.

The reason you see a spit back of gas is the ACR momentarily blows excess gas back into the carb throat and then sucks it back just before TDC for a run. (sounds strange but true)
Pull the spark plug and see if it's wet. dry it off and re-install then
turn off the gas supply to the carb set the throttle to high rpms, no choke and crank engine and it will probably start and run for little while. If you then see it doing same thing again the carb bowl is getting too full. Note that I did not say it's the needle/seat. If it's a Nikki carb the little rubber gasket in the very top of the carb above the plastic piece is bad (it seals above/before the needle/seat or the needle/seat is bad.

Mar 23, 2023#20

F

Forest#2

.003 intake
.005 Ex

Intake is the main one to get set at .003-.005. go for .003 because the ACR (compression release is on the intake valve
BUT
You say the engine cranks fast which indicates that the valve lash may not be the main problem YET.

You say in post #7 when it's cranking fast you see gas blowing back up into the carb throat. seeing gas blowing back is normal on that Model engine when the engine does not start and it's getting too much gas into the carb float due to flooding.

The reason you see a spit back of gas is the ACR (Automatic compression release) momentarily blows excess gas back into the carb throat and then sucks it back just before TDC for a run. (sounds strange but true)

Doubtful it's a valve lash issue if that model engine is cranking fast.

Most likely the engine has weak ignition, flooding or wrong or bad spark plug or weak magneto.

You seem to indicate that it was doing the same thing before you replaced the carb so I would think about ignition.

Mar 23, 2023#21

K

kkjfjns2014

Forest#2 said:
.003 intake
.005 Ex

Intake is the main one to get set at .003-.005. go for .003 because the ACR (Automatic compression release) is on the intake cam lobe of the valve
BUT
You say the engine cranks fast which indicates that the valve lash may not be the main problem YET. (but can be easily checked)
You can see you tube videos of how to do such for your Model Briggs))

You say in post #7 when it's cranking fast you see gas blowing back up into the carb throat. seeing gas blowing back is normal on that Model engine when the engine does not start and it's getting too much gas into the carb float due to flooding.

The reason you see a spit back of gas is the ACR momentarily blows excess gas back into the carb throat and then sucks it back just before TDC for a run. (sounds strange but true)
Pull the spark plug and see if it's wet. dry it off and re-install then
turn off the gas supply to the carb set the throttle to high rpms, no choke and crank engine and it will probably start and run for little while. If you then see it doing same thing again the carb bowl is getting too full. Note that I did not say it's the needle/seat. If it's a Nikki carb the little rubber gasket in the very top of the carb above the plastic piece is bad (it seals above/before the needle/seat or the needle/seat is bad.

It was a couple different Chinese carbs that don't seem to work. My dad pulled the nikki carb off because it wasn't running right. I got it and pulled it apart and seems like it's in ok shape. I'm going to try to clean it really good and see if it'll work. Are you talking about the circle gasket that has all the little passages on it?

Mar 23, 2023#22

K

kkjfjns2014

Forest#2 said:
.003 intake
.005 Ex

Intake is the main one to get set at .003-.005. go for .003 because the ACR (compression release is on the intake valve
BUT
You say the engine cranks fast which indicates that the valve lash may not be the main problem YET.

You say in post #7 when it's cranking fast you see gas blowing back up into the carb throat. seeing gas blowing back is normal on that Model engine when the engine does not start and it's getting too much gas into the carb float due to flooding.

The reason you see a spit back of gas is the ACR (Automatic compression release) momentarily blows excess gas back into the carb throat and then sucks it back just before TDC for a run. (sounds strange but true)

Doubtful it's a valve lash issue if that model engine is cranking fast.

Most likely the engine has weak ignition, flooding or wrong or bad spark plug or weak magneto.

You seem to indicate that it was doing the same thing before you replaced the carb so I would think about ignition.

Mar 23, 2023#23

F

Forest#2

Yes and the two little o rings , itty bitty one that goes around the jet and some have a o ring in the bottom of the bowl.

You can normally get a kit for your carb for about $9 that has all these parts plus other parts. (on fleece bay or otherwise)
Post u[p a part number for the carb you are currently working on and maybe we can then point you towards a kit.
Usually if a Nikki is old and you pull it apart it likes to have new gaskets and o rings when it goes back together.
I have taken parts like the rubber gasket and o rings from the New cheap clones that were not running smooth and make a real Nikki operate ok, but one size does not fit all when the Nikki's are in the loop, different bowls and some difference inside and the jet might be a different size so you are rolling the dice trying to take 2 or 3 and make one.
I have had to return some Amazon Nikki's that would not run correctly.

The Old Walbro LMT carb's are usually to most user friendly on those engines. Briggs used them few years ago before they went to the Nikki and Ruxing carb.
Here is a link to a used LMT on fleece bay. Also here is a link that shows how to repair both types of carbs. Walbro LMT and Nikki plus others
https://outdoorpowerinfo.com/repairs/

Link to view a used Walbro LMT that is a direct replacement bolt on for your Nikki. (with a 30 day warranty)They say it runs good.

Carburetor for Briggs & Stratton 696179 Original Walbro LMT Replaces Nikki Carb | eBay

Find many great new & used options and get the best deals for Carburetor for Briggs & Stratton 696179 Original Walbro LMT Replaces Nikki Carb at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Mar 23, 2023#24

K

kkjfjns2014

Thank you for all that information I really appreciate it. I think I'll try the gaskets from the clone carb first and it still won't work good I'll order a kit.

The numbers on it are:
697203
G02703
5X19 C

Forest#2 said:
Yes and the two little o rings , itty bitty one that goes around the jet and some have a o ring in the bottom of the bowl.

You can normally get a kit for your carb for about $9 that has all these parts plus other parts. (on fleece bay or otherwise)
Post u[p a part number for the carb you are currently working on and maybe we can then point you towards a kit.
Usually if a Nikki is old and you pull it apart it likes to have new gaskets and o rings when it goes back together.
I have taken parts like the rubber gasket and o rings from the New cheap clones that were not running smooth and make a real Nikki operate ok, but one size does not fit all when the Nikki's are in the loop, different bowls and some difference inside and the jet might be a different size so you are rolling the dice trying to take 2 or 3 and make one.
I have had to return some Amazon Nikki's that would not run correctly.

The Old Walbro LMT carb's are usually to most user friendly on those engines. Briggs used them few years ago before they went to the Nikki and Ruxing carb.
Here is a link to a used LMT on fleece bay. Also here is a link that shows how to repair both types of carbs. Walbro LMT and Nikki plus others
https://outdoorpowerinfo.com/repairs/

Link to view a used Walbro LMT that is a direct replacement bolt on for your Nikki. (with a 30 day warranty)They say it runs good.

Carburetor for Briggs & Stratton 696179 Original Walbro LMT Replaces Nikki Carb | eBay

Find many great new & used options and get the best deals for Carburetor for Briggs & Stratton 696179 Original Walbro LMT Replaces Nikki Carb at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Mar 23, 2023#25

K

kkjfjns2014

kkjfjns2014 said:
Thank you for all that information I really appreciate it. I think I'll try the gaskets from the clone carb first and it still won't work good I'll order a kit.

The numbers on it are:
697203
G02703
5X19 C

Mar 23, 2023#26

F

Forest#2

Review that link I sent about carb repairing. Very good do and don't info in that link.

Mar 23, 2023#27

K

kkjfjns2014

Forest#2 said:
Review that link I sent about carb repairing. Very good do and don't info in that link.

That's an awesome and detailed guide. Thank you for sharing!

Mar 23, 2023#28

D

DaveTN

After getting the fuel shutoff working properly, why not do
a Gasoline IV line and as ILENGINE said the fuel level may
drop below gravity feed and starve the engine for fuel. It
should run on an elevated portable tank or another push
mower gas tank and see if it continues to run ok. And Welcome
to the LMF!

Mar 25, 2023#29

doug9694

kkjfjns2014 said:
Hello all, I have a 2006 briggs and stratton 18.5 HP [31N707] engine that came off a craftsman. We put it on a small ariens zero turn. It worked very well for awhile, then got it where it wouldn't run unless the choke was on. Eventually it quit running all together. After this my dad parked it and it sat for 2 years.

I decided to try and fix it for him this year. There was water in the gas, so I took that tank off and drained it and dried it in the sun for a few days. I put it back on put in fresh gas. I also replaced the carb and all fuel lines and vacuum lines and filters. I put the choke on and started it and it ran for about 10 seconds, I took the choke off and now it's back to not running at all again. Tried tinkering with the air/fuel mix a bit, still no luck. If you feed it gas directly into the carb it will run. It has good spark, everything else seems to be functioning, I have no idea what else to do. I'm about to pull my hair put. Any advice on next steps would be greatly appreciated. Thank you.

Could be the fuel shut off solenoid if it has one.

Mar 25, 2023#30

S

smallenginerepairs

kkjfjns2014 said:
Hello all, I have a 2006 briggs and stratton 18.5 HP [31N707] engine that came off a craftsman. We put it on a small ariens zero turn. It worked very well for awhile, then got it where it wouldn't run unless the choke was on. Eventually it quit running all together. After this my dad parked it and it sat for 2 years.

I decided to try and fix it for him this year. There was water in the gas, so I took that tank off and drained it and dried it in the sun for a few days. I put it back on put in fresh gas. I also replaced the carb and all fuel lines and vacuum lines and filters. I put the choke on and started it and it ran for about 10 seconds, I took the choke off and now it's back to not running at all again. Tried tinkering with the air/fuel mix a bit, still no luck. If you feed it gas directly into the carb it will run. It has good spark, everything else seems to be functioning, I have no idea what else to do. I'm about to pull my hair put. Any advice on next steps would be greatly appreciated. Thank you.

you have fuel restriction. check your fuel pump, and make sure when cranking your getting a good fuel supply. If you're getting good fuel supply it's the carb. Many aftermarket carbs are made in China, and they do not have qualoty control. They do not check carbs before they are sold, so a brand new carb can have a manufacture flaw.

Mar 25, 2023#31

K

kkjfjns2014

smallenginerepairs said:
you have fuel restriction. check your fuel pump, and make sure when cranking your getting a good fuel supply. If you're getting good fuel supply it's the carb. Many aftermarket carbs are made in China, and they do not have qualoty control. They do not check carbs before they are sold, so a brand new carb can have a manufacture flaw.

The pump is providing plenty of gas as it cranks. I agree, it's probably a Chinese knock off that wasn't built properly.

Mar 25, 2023#32

R

RGSERVICES

kkjfjns2014 said:
There is a solenoid shut off on the bottom, but I cut it off because the wire wasn't giving a reliable connection. I did notice it blowing some gas back and found out that means the valves may be out of whack. Do you know what the valve clearances on this engine are?

i should power the solenoid back up, you can do it with a live and earth directly off the battery to test it first if you want too.

Mar 25, 2023#33

Z

Zue

I set the Briggs valve gaps at .004. / .006 for intake / exhaust. Cutting wires to fuel cutoff solenoid on bottom of carb will do nothing if solenoid is stuck in upward position. Solenoid will still block flow. If you replaced the carb, it should’ve come with a new fuel solenoid. Don’t bother cutting up the new one, just use the old one from the original carburetor and cut it up. The solenoids can cost up to $80 each if you buy them direct from Briggs and Stratton. Of course the Chinese carburetor ones would be much cheaper.

Mar 25, 2023#34

K

kkjfjns2014

Zue said:
I set the Briggs valve gaps at .004. / .006 for intake / exhaust. Cutting wires to fuel cutoff solenoid on bottom of carb will do nothing if solenoid is stuck in upward position. Solenoid will still block flow. If you replaced the carb, it should’ve come with a new fuel solenoid. Don’t bother cutting up the new one, just use the old one from the original carburetor and cut it up. The solenoids can cost up to $80 each if you buy them direct from Briggs and Stratton. Of course the Chinese carburetor ones would be much cheaper.

I've posted about 4 times I didn't cut the wires, just the plunger on the end of it. I've been swapping the one I cut around on the carbs I've been using so I don't waste multiple of them.

Mar 25, 2023#35

F

Forest#2

What I've done to get a test run so as to bypass the fuel tank/fuel pump is to take a 12 to 24 inch fuel hose and connect it directly to the carb input and then tie the fuel line elevated and take a small funnel and fill the hose with fuel and then start the engine. A small engine will run long time with a 5/16 hose full of fuel.
I also have a plastic fuel tank with hose/petcock and filter for subbing if I want to do a run/load test or need a more permanent supply when testing.

Mar 25, 2023#36

K

kkjfjns2014

Forest#2 said:
What I've done to get a test run so as to bypass the fuel tank/fuel pump is to take a 12 to 24 inch fuel hose and connect it directly to the carb input and then tie the fuel line elevated and take a small funnel and fill the hose with fuel and then start the engine. A small engine will run long time with a 5/16 hose full of fuel.
I also have a plastic fuel tank with hose/petcock and filter for subbing if I want to do a run/load test or need a more permanent supply when testing.

There is no issue getting fuel to the carb. I've verified this several times. It has something to do with how the carb is feeding it into the engine.

Mar 25, 2023#37

F

Forest#2

Right: I did notice that.
I was just indicating how to quickly test a small engine fuel supply using a fuel hose if no spare tank was readily available as a test.

Good luck on your Nikki overhaul and keep the LMT carb in mind that I mentioned as a replacement. I keep a eye and ear open for the Walbro LMT carbs so as to use as spare replacements for the Nikki's.

I've seen some of them Nikki clones quite often not operate correctly when new. Really erratic and some cold natured. Some rough at high rpms, others rough at idle, some spit back like valve issues.

Mar 25, 2023#38

K

kkjfjns2014

Forest#2 said:
Right: I did notice that.
I was just indicating how to quickly test a small engine fuel supply using a fuel hose if no spare tank was readily available as a test.

Good luck on your Nikki overhaul and keep the LMT carb in mind that I mentioned as a replacement. I keep a eye and ear open for the Walbro LMT carbs so as to use as spare replacements for the Nikki's.

I've seen some of them Nikki clones quite often not operate correctly when new. Really erratic and some cold natured. Some rough at high rpms, others rough at idle, some spit back like valve issues.

Good advice

, I'll keep the carb in mind thank you. I just got done cleaning the nikki carb out real good. I'm going to try it out within the next couple of days and see if she'll run.

Mar 25, 2023#39

T

TobyU

Okay, several things. I understood from the beginning that you cut the plunger tip off and not the wire and someone else misunderstood that. That person did talk about doing that as a poor man's fix and the other text who insist on doing things a certain way of replacing Parts need to not worry about it because it isn't in their shop and anyone that would replace that solenoid that had been cut off when someone brings to your shop is really doing a disservice for the customer and costing them needless money and that's what gives repair shops a bad name and one of the three reasons I actually run a repair shop because I won't do it that old school established way.
The fact is that solenoid has been pushed if not required by the EPA or at least it makes them feel all warm and fuzzy inside and it was originally designed or at least named to prevent the popping sound which some people call a backfire after you turn off the engine but it's not really a backfire. It's the unburnt fuel as the engine spins down which pulls up the vapors in the muffler and then when the rich auction at the outlet of the muffler allows enough in to hit those papers they explode and you hit the pop.
The sad part is what is designed to do... It rarely even does!
Anyone who's worked with a good number of riding mowers over the past 25 years can tell you time and time again how they have had mowers and even owners have had these were that solenoid is functioning absolutely the way it's supposed to but they're more still routinely 4 to 6 times out of 10 pops like that when they shut it off.
It's off and recommended to idle them down for 15 to 20 seconds before turn them off is this sometimes helps but still for 20 years it was the most overpriced part on any riding lawn mower and they took advantage of that being 48 to $60 minimum but luckily they popped in on eBay a few years ago at $6.84 so now they're usually under 11 so it's tolerable but still kind of a waste to replace them since they don't work but less than half the time anyways.
Okay enough of that soapbox ranting of facts but it sounds to me like you're not getting enough gas and not too much. Something probably floated around and clogged up the jet inside the carb.
I don't remember from all the previous posts if it's a walbro or Nikki style but regardless I would take the bowl off and make sure the jet is clear. The Nikki is often put in improperly and put in from the bottom when it's supposed to go in from the top so when you slide the bowl on with the plastic piece inside it pushes the jet and holds it into the proper place. It will still work on the bottom but people often lose them and this will cause extremely rich condition but if you can't get the mower to run with the air filter off and the choke off and especially if you can spray a little bit of car cleaner or gas into the intake carb hole and then get it to run a few seconds it's almost certainly got something clogging up the jet inside.
Even new ones do this with a piece of plastic or metal or whatever manufacturing piece left that will float around and clog the hole.
Always go back to the basics. If it won't start and run leave the choke off and spray some card cleaner in the hole for a couple of seconds and then try it. If you do this three times and you still don't get it to hit it all then and only then take out the spark plug and see if it sucked and while it's out see if it will spark when you spend the engine with it out plugged back into the plug wire and then put your finger in the hole or do a compression check for those of you who just must screw a compression tester into them but that's such a moot point of what the number is.
With their ACR setup it's a joke anyways. All I need to do is stick my finger in the hole and feel it go puff puff puff puff and make sure it doesn't suck on my finger and make sure it's a rhythmic consistent puff puff puff with no double puffs etc and I know exactly that the engine has enough compression to run.
Now, getting back to the previous part though I wish people wouldn't throw Parts at things so quickly. You hardly ever need a new carburetor. You just need your old and cleaned out. Typically the old carburetor on your machine is a better quality and will last longer than I knew when you will purchase today regardless of which brand it is so stick with the old and clean them out.
I think yours is a fuel issue now and not getting enough of it so try some car cleaner in the hall and if it hits and runs pull the bow off of the carb and go from there.

Mar 25, 2023#40

T

TobyU

kkjfjns2014 said:
Hello all, I have a 2006 briggs and stratton 18.5 HP [31N707] engine that came off a craftsman. We put it on a small ariens zero turn. It worked very well for awhile, then got it where it wouldn't run unless the choke was on. Eventually it quit running all together. After this my dad parked it and it sat for 2 years.

I decided to try and fix it for him this year. There was water in the gas, so I took that tank off and drained it and dried it in the sun for a few days. I put it back on put in fresh gas. I also replaced the carb and all fuel lines and vacuum lines and filters. I put the choke on and started it and it ran for about 10 seconds, I took the choke off and now it's back to not running at all again. Tried tinkering with the air/fuel mix a bit, still no luck. If you feed it gas directly into the carb it will run. It has good spark, everything else seems to be functioning, I have no idea what else to do. I'm about to pull my hair put. Any advice on next steps would be greatly appreciated. Thank you.

Also, on these valves. The 31xxxxand 33xxxxx and most of these Briggs engines set with the Piston one quarter inch past top dead center so going down in the bore at least one quarter inch after top dead center when both valves are closed on the compression stroke, and even better if you want to go an inch or two down because it's irrelevant after that point until you get all the way to bottom dead center....and most of them sat at 004 - - .006 intake and .005 to .007 exhaust.
There are not a whole lot that set at .005 for both except your Kohler courage.
Since these numbers are also close it often works for people so then they just decide that that's the proper spec when it's actually not.
Also, since they wear loose when you pull these valve covers off you typically find them in the at least .010 to .012 range if not looser. The intake is more important than the exhaust because that's where your ACR works off of and it will be hard to crank over and act like it's bouncing back against the rubber band wall if your intake valve is too loose.
The black smoke you mentioned though is NOT indicative of the valves being out of whack. Technically, only being hard to start is indicative of the valves being out of whack. If the thing is running the valves are good enough for all intents and purposes but I would hate to see them too tight but that would only happen if someone adjusts them too tight because they don't wear tight.
Valves being tight is what burns them because they only cool when they're closed.
But other than being hard to start, if it's smoking or low on power or anything else.. it's not the valve adjustment.

Mar 25, 2023#41

smhardesty

Thank you, TobyU. I now know that at least one guy actually caught what I was saying.

Fact: My own Craftsman lawn tractor began shutting off while I was mowing, and it was the very first year I owned the thing. The first time it did it, it took a while before I thought to tap the side of the fuel bowl. It took me a while to think about the shutoff solenoid. The second and third time it decided to just shutoff, I immediately tapped the fuel bowl and it fired right back up. I managed to finish the mowing and that evening I got online to order a new solenoid. The price was $92. I was a bit peeved. The following day I went and bought an old time, cheap, manual shutoff valve and stuck it in the fuel line between the tank and the fuel filter. Now, when I change my fuel filter, I no longer have gas running all over. If I know I'm going to change the fuel filter, I shut the manual valve off, then let the engine run until it dies. No fuel is left in the line or filter to accidentally spill out. Then, after putting the manual valve in the line, I turned it off, pulled the bowl, and cut the plunger off. Problem solved and for about 5 bucks versus the $92 replacement cost of the solenoid.

I also ALWAYS let my small engines idle for a minimum of 3 minutes after using the equipment. I have NEVER heard any sort of backfiring or any other noises when I shut the equipment off. You are correct in saying that even with the solenoid working as it is supposed to, an engine can still produce the backfiring.

Mar 25, 2023#42

T

TobyU

smhardesty said:
Thank you, TobyU. I now know that at least one guy actually caught what I was saying.

Fact: My own Craftsman lawn tractor began shutting off while I was mowing, and it was the very first year I owned the thing. The first time it did it, it took a while before I thought to tap the side of the fuel bowl. It took me a while to think about the shutoff solenoid. The second and third time it decided to just shutoff, I immediately tapped the fuel bowl and it fired right back up. I managed to finish the mowing and that evening I got online to order a new solenoid. The price was $92. I was a bit peeved. The following day I went and bought an old time, cheap, manual shutoff valve and stuck it in the fuel line between the tank and the fuel filter. Now, when I change my fuel filter, I no longer have gas running all over. If I know I'm going to change the fuel filter, I shut the manual valve off, then let the engine run until it dies. No fuel is left in the line or filter to accidentally spill out. Then, after putting the manual valve in the line, I turned it off, pulled the bowl, and cut the plunger off. Problem solved and for about 5 bucks versus the $92 replacement cost of the solenoid.

I also ALWAYS let my small engines idle for a minimum of 3 minutes after using the equipment. I have NEVER heard any sort of backfiring or any other noises when I shut the equipment off. You are correct in saying that even with the solenoid working as it is supposed to, an engine can still produce the backfiring.

Yep, I have hated that solenoid for decades because for 25 years it has been the most overpriced ripoff part on a lawn mower..
They were 48 to $68 minimum and many of them were right in the 90s like you just stated. I was so happy to see a few years ago when I started popping in for under $10 and half of the cheap aftermarket carbs you buy will already have one of them on there also so it's like a two-for-one freebie deal.
I don't really think you have to idle your machines down for 3 minutes before you shut them off but it's not a bad idea to let them out or down for about 30 seconds but sometimes only 10 or 15 will do the trick for the popping afterwards because it's not really about the heat as it is the fact that when the engine turns off from a faster speed it's going to Coast longer than from a slower speed so you're going to have more unburnt fuel filling up the muffler.
Kohler actually issued a TSB saying exactly that just to let it idle for 30 seconds before you turned it off.
Since we're talking about letting equipment run I will mention one thing that many people do that's very bad for their equipment.
They will mow their entire yard or even several acres and get the mower as hot as it's going to get then they will finish mowing and turn off the blades. Then, the unfortunate part, many of them will lower the engine speed to a medium or even lowest idle speed and then ride the machine back to the garage or barn or wherever to park it.
This is a terrible practice! You are still moving the entire weight of the machine and the person and your transmission which has gotten to its peak temperature will now spike in temperatures sometimes 20 to 40° if you're riding it far enough.
That little 7-in fan on top of the hydro transmission on most of these units today is directly proportionate to the engine speed and your engine speed goes from right around 3,000 RPMs down to 1300.
That is a crazy amount of airflow reduction and you're still doing the same amount of work so it's a bad idea. It also tends to overheat the engines a little bit too but of course engine temperature always goes up slightly right after you turn them off.
I always tell people, if it's mowing or moving, the engine needs to be at the full operating speed.

Mar 25, 2023#43

A

Alton R

kkjfjns2014 said:
Hello all, I have a 2006 briggs and stratton 18.5 HP [31N707] engine that came off a craftsman. We put it on a small ariens zero turn. It worked very well for awhile, then got it where it wouldn't run unless the choke was on. Eventually it quit running all together. After this my dad parked it and it sat for 2 years.

I decided to try and fix it for him this year. There was water in the gas, so I took that tank off and drained it and dried it in the sun for a few days. I put it back on put in fresh gas. I also replaced the carb and all fuel lines and vacuum lines and filters. I put the choke on and started it and it ran for about 10 seconds, I took the choke off and now it's back to not running at all again. Tried tinkering with the air/fuel mix a bit, still no luck. If you feed it gas directly into the carb it will run. It has good spark, everything else seems to be functioning, I have no idea what else to do. I'm about to pull my hair put. Any advice on next steps would be greatly appreciated. Thank you.

Have you checked if the carburetor to see if it has a fuel solenoid on the bottom of the float bowl. They go bad and sometimes they stick closed. I would remove the carburetor and clean it good and check the solenoid to see if it's free to move. If it's free make sure it's working by applying voltage to it.
Be careful about starting a fire

.
Do it while away from any fuel.

Mar 25, 2023#44

G

Gescha

kkjfjns2014 said:
Hello all, I have a 2006 briggs and stratton 18.5 HP [31N707] engine that came off a craftsman. We put it on a small ariens zero turn. It worked very well for awhile, then got it where it wouldn't run unless the choke was on. Eventually it quit running all together. After this my dad parked it and it sat for 2 years.

I decided to try and fix it for him this year. There was water in the gas, so I took that tank off and drained it and dried it in the sun for a few days. I put it back on put in fresh gas. I also replaced the carb and all fuel lines and vacuum lines and filters. I put the choke on and started it and it ran for about 10 seconds, I took the choke off and now it's back to not running at all again. Tried tinkering with the air/fuel mix a bit, still no luck. If you feed it gas directly into the carb it will run. It has good spark, everything else seems to be functioning, I have no idea what else to do. I'm about to pull my hair put. Any advice on next steps would be greatly appreciated. Thank you.

You're jets in the carb are clogged up.
Remove them and clean all passages.

Mar 25, 2023#45

S

STEVES

Your pictured carb has separate 'o' ring at fuel inlet,bowl gasket #698781, newer model carbs have as part of the bowl gasket #695426.

Mar 25, 2023#46

K

Kierw

kkjfjns2014 said:
Hello all, I have a 2006 briggs and stratton 18.5 HP [31N707] engine that came off a craftsman. We put it on a small ariens zero turn. It worked very well for awhile, then got it where it wouldn't run unless the choke was on. Eventually it quit running all together. After this my dad parked it and it sat for 2 years.

I decided to try and fix it for him this year. There was water in the gas, so I took that tank off and drained it and dried it in the sun for a few days. I put it back on put in fresh gas. I also replaced the carb and all fuel lines and vacuum lines and filters. I put the choke on and started it and it ran for about 10 seconds, I took the choke off and now it's back to not running at all again. Tried tinkering with the air/fuel mix a bit, still no luck. If you feed it gas directly into the carb it will run. It has good spark, everything else seems to be functioning, I have no idea what else to do. I'm about to pull my hair put. Any advice on next steps would be greatly appreciated. Thank you.

Hello, sounds like a fuel pump issue, it runs when you pour fuel directly into carb, then dies when that fuel is exhausted, no new fuel coming in to replace it.. You’ve replaced the carb, a new fuel pump with it should give you great results…

Mar 25, 2023#47

K

Kierw

kkjfjns2014 said:
Hello all, I have a 2006 briggs and stratton 18.5 HP [31N707] engine that came off a craftsman. We put it on a small ariens zero turn. It worked very well for awhile, then got it where it wouldn't run unless the choke was on. Eventually it quit running all together. After this my dad parked it and it sat for 2 years.

I decided to try and fix it for him this year. There was water in the gas, so I took that tank off and drained it and dried it in the sun for a few days. I put it back on put in fresh gas. I also replaced the carb and all fuel lines and vacuum lines and filters. I put the choke on and started it and it ran for about 10 seconds, I took the choke off and now it's back to not running at all again. Tried tinkering with the air/fuel mix a bit, still no luck. If you feed it gas directly into the carb it will run. It has good spark, everything else seems to be functioning, I have no idea what else to do. I'm about to pull my hair put. Any advice on next steps would be greatly appreciated. Thank you.

I’m sorry, I didn’t see where you had already replaced the pump, I take that back, the fuel solenoid fix sounds very plausible..

Mar 26, 2023#48

E

Elkins45

TobyU said:
The intake is more important than the exhaust because that's where your ACR works off of and it will be hard to crank over and act like it's bouncing back against the rubber band wall if your intake valve is too loose.

I had to replace the sump gasket on my Briggs Intek twin last fall. While I had it off I went ahead and adjusted the valves.

For the last several years it was initially difficult to turn over. By that I mean when the ignition was turned it would crank maybe a quarter rotation and then just stall. If I kept holding the ignition key on it would finally (2-3 seconds) crank the rest of the way around and then start. I thought it was a symptom of a weak starter motor.

The first time I started it after doing the valves it cranked like brand new! It finally dawned on me that the hesitation I had been experiencing was the loss of compression release because the intake valve was too loose. You're never too old to learn something new, and I guess I'm lucky I didn't burn out my starter from doing this repeatedly over the last few years.

Mar 26, 2023#49

K

kkjfjns2014

Kierw said:
I’m sorry, I didn’t see where you had already replaced the pump, I take that back, the fuel solenoid fix sounds very plausible..

I cut the fuel solenoid plunger off to remedy any issues it would have. Tried to start it today and it's blowing gas out of the exhaust with the nikki carb back on it. So it's obviously flooding right? How do I remedy that?

Mar 26, 2023#50

K

kkjfjns2014

Elkins45 said:
I had to replace the sump gasket on my Briggs Intek twin last fall. While I had it off I went ahead and adjusted the valves.

For the last several years it was initially difficult to turn over. By that I mean when the ignition was turned it would crank maybe a quarter rotation and then just stall. If I kept holding the ignition key on it would finally (2-3 seconds) crank the rest of the way around and then start. I thought it was a symptom of a weak starter motor.

The first time I started it after doing the valves it cranked like brand new! It finally dawned on me that the hesitation I had been experiencing was the loss of compression release because the intake valve was too loose. You're never too old to learn something new, and I guess I'm lucky I didn't burn out my starter from doing this repeatedly over the last few years.

Do these motors have a timing key? Could it have lost time?

Mar 26, 2023#51

K

kkjfjns2014

kkjfjns2014 said:
Do these motors have a timing key? Could it have lost time?

Ok everyone so to recap, this is where I'm at.

I've tried 3 different carbs, two of them flood the cylinder and soaked the spark plug completely. The other one didn't seem to feed it any gas at all. One of the two flooded ones was a Nikki, the other two were generic Chinese replacement carbs.

The fuel shut off solenoid is a NON ISSUE. I've cut the plunger off one and have been swapping it around as I try carbs.

It has clean spark, good new gas, and I already adjusted the valves.

I'm about ready to throw a match on this thing. I don't know why the hell it just won't run. When I first try to start it it acts like it wants to start and will chug a few times before it floods with gas then it won't even try to start even after I dry out the spark plug and cylinder. If I leave it sit for a day it'll do the same thing the next day.

I officially hate briggs and stratton motors. I've never had this many issues out of any other brand ever. I have a kohler and it doesn't give me half this much shit. I've had a few other briggs motors and they always seems to hit the shitter and become unfixable way to fast.

Mar 26, 2023#52

smhardesty

First, You problem isn't just because it's a Briggs engine. There are a lot of guys that would argue that they hate Kohler because they had a similar problem they never could get fixed on a Kohler, but they never, ever had a problem with a Briggs. So, rule that complaint null and void.

Secondly, maybe you just need to do a true and proper diagnosis of the problem, following a logical troubleshooting sequence. I have attached a very extensive troubleshooting flow chart. Maybe you should go back and start troubleshooting step by step.

https://images34.fotki.net/v1681/fileAjMx/a7ac4/2/3733132/14239300/Diagnosticflownostart.pdf

Mar 26, 2023#53

B

bertsmobile1

kkjfjns2014 said:
I cut the fuel solenoid plunger off to remedy any issues it would have. Tried to start it today and it's blowing gas out of the exhaust with the nikki carb back on it. So it's obviously flooding right? How do I remedy that?

Depending upon which Nikki carb you have you need to clean the carb and if needed replace the float needle
If it has the white plastic jet holder with the complex O ring style gasket they are prone to leaking around the inlet O ring
Note there are 2 styles of this carb & thus 2 gaskets
Full details in pictures on out door power info web page

Mar 26, 2023#54

B

bertsmobile1

Mower engines are made to a price not to a quality level
And as Kohlers are more expensive it should be no surprise they give fewer problems apparently .
However you have to view this in contex that B & S probably outnumber Kohlers 300 :1
I hate B & S engines because they are designed by accountants so every fastener is the smallest one that will do the job in what form that is cheapest to buy
So to pull one down you often need better than 10 different tools
Most kohlers need only a 10mm socket & either a torx or std screwdriver
On top of that people who buy the cheapest by & large do not respect their gear and abuse it without any thoughts of maintenance till it goes bang & stops
Then they ring me and ask "how much it cost to service their mower "
And of course no one ever reads their owners manual till their mower stops running.

As mentioned above very few do a proper diagnosis and in may cases they fix the symptoms & not the problem.

Mar 26, 2023#55

B

Brucecooke212

kkjfjns2014 said:
Hello all, I have a 2006 briggs and stratton 18.5 HP [31N707] engine that came off a craftsman. We put it on a small ariens zero turn. It worked very well for awhile, then got it where it wouldn't run unless the choke was on. Eventually it quit running all together. After this my dad parked it and it sat for 2 years.

I decided to try and fix it for him this year. There was water in the gas, so I took that tank off and drained it and dried it in the sun for a few days. I put it back on put in fresh gas. I also replaced the carb and all fuel lines and vacuum lines and filters. I put the choke on and started it and it ran for about 10 seconds, I took the choke off and now it's back to not running at all again. Tried tinkering with the air/fuel mix a bit, still no luck. If you feed it gas directly into the carb it will run. It has good spark, everything else seems to be functioning, I have no idea what else to do. I'm about to pull my hair put. Any advice on next steps would be greatly appreciated. Thank you.

Make sure the return choke spring is on and works properly

Mar 26, 2023#56

J

jenneir

StarTech said:
And then this is done and the engine come into my shop it gets a new solenoid and customer gets the bill for being stupid. Sorry but is how I feel about it but it is one stupid thing that can fixed. Other stupid things can't be fixed.

Oh btw those fuel solenoids are cleanable.

Mar 27, 2023#57

smhardesty

???, jenneir?

Mar 27, 2023#58

B

biggertv

Could be a bad Coil even if you have Spark. Usually it dies when Hot is first symptom. Spark will be Yellow instead of Blue. If you have Fuel and Compression...

Mar 27, 2023#59

K

kkjfjns2014

biggertv said:
Could be a bad Coil even if you have Spark. Usually it dies when Hot is first symptom. Spark will be Yellow instead of Blue. If you have Fuel and Compression...

Wow, I noticed a yellow spark when I was testing the plug and didn't even know that was a thing. That is awesome. I'll be ordering a new coil today

Mar 27, 2023#60

B

biggertv

Don't pay too much! I get most of my parts from Amazon. Look for free returns. Most are made in china anyway... Check Reviews and sort by confirmed purchase. Your first clue was Wet Spark Plugs. Good Luck!

Mar 27, 2023#61

B

biggertv

While you're in there check the Flywheel Key. Rare on a Rider but I've seen it especially if Nut is not torqued properly. Even if not sheared, a worn Key Way will give you spark but wet plugs.

Mar 27, 2023#62

K

kkjfjns2014

biggertv said:
While you're in there check the Flywheel Key. Rare on a Rider but I've seen it especially if Nut is not torqued properly. Even if not sheared, a worn Key Way will give you spark but wet plugs.

How would I check that? Taking the top flywheel off?

Mar 27, 2023#63

T

TobyU

kkjfjns2014 said:
Wow, I noticed a yellow spark when I was testing the plug and didn't even know that was a thing. That is awesome. I'll be ordering a new coil today

As someone else said earlier, do a thorough and proper diagnosis before you throw more parts at the machine.
This happens way too often with homeowners and by the second or third attempt they stumble into it and get it right and it just creates positive reinforcement of doing a bad pattern in the future.
I understand it's frustrating you have to do something but we need to back up before you waste money on a coil and like someone else said make sure you order one off eBay or Amazon so it will be $16 shipped to your door instead of paying 60 at a lawnmower shop or for a Briggs & Stratton brand.
Two of the carbs flooded out one wouldn't run it all but the question now is if you take the plug out and put a fresh dry plug in there can you get it to run on carb cleaner spraying it in the intake of the carb????
If you can then it certainly isn't the coil at least not unless it runs for a while and gets hot and then they coil breaks down and then it dies and then starts the process all over again once it cools off but that's a secondary diagnosis. You are well before that now.
Also, make sure the spark plug is gapped no greater than .030.
That is the spec but I like to get them about .027 to .028. in fact, it makes little difference as you could gap it at .020 or .025 and you wouldn't notice a bit of difference in the performance or the power but as it gets older and more carbon on it and the coil gets weaker or if the coil is getting borderline and ready to fail in the next couple of years anyways, it will last longer and you'll get a more consistent stronger spark with a smaller gap.
So tighteris better than looser on the spark plug gap -- within reason!

So get back to the basics. If the cylinder isn't flooded out and the plugs not wet now you just want to make sure the plug Sparks when you spend the engine over by looking at the spark jumping at the tip and it should be a bluish to whitish color. Red will still fire and run but it is weaker and yellow you really hardly ever see I guess unless it's bright and sunny out and it's hard to see anything.
If the cylinder is dry and the plug is not fouled out and you spin the engine over at normal speed and provide a fuel source into the intake, if the engine is mechanically sound which means the valves working properly and having compression and having spark...it will run for a few seconds until the fuel source you provide runs out.
In fact, you could take the carburetor off and lay it on the ground and squirt the carb cleaner in the side of the engine where the hole is and it would do the same thing but that's not a good idea because they will be no method to govern it and you could overrev and blow it up or grenade your internal governor/slinger because with no carb on the engine to block off the air flow the only way you have to stall it out until it runs out of fuel is to put a thick rag over the hole and kill its intake of air which is a little hard to do.
My point is that the carb has nothing to do with the engine actually running or not.... Providing fuel and at the proper amount and ratio is what determines whether it a mechanically sound engine will run or not. That just happens to be what the carburetor is supposed to do.
So go get that can of car cleaner or a little spray bottle and pour some gas in it and check your spark plug and see if this thing will run for three or four seconds at a time on an external fuel source.

Mar 27, 2023#64

smhardesty

Well stated, TobyU. He most definitely needs to diagnose, step by step, instead of taking guesses and throwing more money at it. Yeah, eventually he might actually hit a combination of new and old parts that result in the engine starting and running, but the real problem might not ever be determined. If you throw enough new parts at ANY engine, it will eventually run, but by that time you might have a complete new engine sitting in front of you. Building an engine by buying new parts will make for an awfully expensive engine.

Mar 27, 2023#65

B

biggertv

kkjfjns2014 said:
How would I check that? Taking the top flywheel off?

At least remove the nut and washer so you can see the key way. It's probably ok unless it's been removed before and not torqued properly.

Mar 28, 2023#66

F

Forest#2

Lots of good info previously:

Just a hint that has been mentioned.
Turn off the gas to the carb.
Start testing with a dry clean spark plug and also crank the engine over se3veral times with the plug out to purge out any flood gas that might be in the cylinder.
Set the throttle at just about midway.
Squirt spoonful of gas into the carb throat while it's cranking fast.
If it briefly tries to run the engine needs gas from the carb to run.

If it don't attempt to briefly run, it has ignition or compression issues.
Does the engine have any compression? (at least 80psi)

You may have started out with two issues with the engine, a bad carb and something else and sometimes two issues are harder to sort out.

Let us know how this test goes???

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Briggs 18.5 hp Wont Run

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Carburetor for Briggs & Stratton 696179 Original Walbro LMT Replaces Nikki Carb | eBay

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