Briggs 18.5 hp Wont Run

[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.

 

[TobyU]

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.

 

[Alton R]

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.

 

[Gescha]

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.

 

[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.

 

[Kierw]

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…

 

[Kierw]

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..

 

[Elkins45]

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.

 

[kkjfjns2014]

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?

 

[kkjfjns2014]

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?