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Briggs and Stratton engine runs rough sputters after it gets warm

#1

J

jgaspelin

I have cleaned carburetor, changed spark plug, got new gas, and changed flywheel key and adjusted magneto spacing. The engine runs cuts entire lawn but sputters instead of running smoothly. I also put stabil in gas.


#2

I

ILENGINE

And which of the 5000 briggs engine are we trying to fix. Model, type, and code allows us to see what you are working on.


#3

J

jgaspelin

It is a 725 percent ex 190 cc


#4

J

jgaspelin

725 ex 190cc


#5

J

jgaspelin

D18461ac is the number


#6

I

ILENGINE

Get yourself a spark tester. The type that you can watch while the engine is running. You are looking for a misfire. if one is detected, could be a spark plug problem (read years ago that champion plug considered a 25% misfire as acceptable) an ignition module problem, or also check for a shorting kill wire from the stop switch next the brake to the ignition module.

If that all pans out then time to start looking at compression, valve clearances, and possibly still a carb issue.


#7

reynoldston

reynoldston

jgaspelin said:
I have cleaned carburetor, changed spark plug, got new gas, and changed flywheel key and adjusted magneto spacing. The engine runs cuts entire lawn but sputters instead of running smoothly. I also put stabil in gas.
Click to expand...

As a rule when a engine starts to run rough after it warms up the first thing I look for is a tight valve. Another thing that effects a warm engine running rough is a coil going bad. You need to look for something temperature related. Cleaning carburetor, spark plug, gas, flywheel key and mag spacing wouldn't have anything to do with the engine temperature.


#8

J

jgaspelin

Three different spark plugs with same result. Could the magneto be bad?


#9

J

jgaspelin

reynoldston said:
As a rule when a engine starts to run rough after it warms up the first thing I look for is a tight valve. Another thing that effects a warm engine running rough is a coil going bad. You need to look for something temperature related. Cleaning carburetor, spark plug, gas, flywheel key and mag spacing wouldn't have anything to do with the engine temperature.
Click to expand...

Any way to tell if coil is bad?


#10

reynoldston

reynoldston

jgaspelin said:
Three different spark plugs with same result. Could the magneto be bad?
Click to expand...

As said earlier if it is operating temp related it isn't spark plugs, so maybe you should put three spark plugs into it. Now for coil the only test you might be able to do is, make sure it will throw a good 1/4 inch spark after you heat it up the coil with a hot air blow dryer. Other then that have it tested at a repair shop with the equipment to test coils.


#11

B

bertsmobile1

jgaspelin said:
Any way to tell if coil is bad?
Click to expand...

ILENGINE told you how to do it way back in post no 5.
For novices I recommend you go one better & buy a COLOR TUNE from a company called GUNSONS.
They are in the UK and do web sales to the USA.
Look at the video on their site to see how it works.
Then at least you will definitely know if you have an electrical problem or a fuel problem and weather a fuel problem is rich or lean.


#12

reynoldston

reynoldston

bertsmobile1 said:
ILENGINE told you how to do it way back in post no 5.
For novices I recommend you go one better & buy a COLOR TUNE from a company called GUNSONS.
They are in the UK and do web sales to the USA.
Look at the video on their site to see how it works.
Then at least you will definitely know if you have an electrical problem or a fuel problem and weather a fuel problem is rich or lean.
Click to expand...

Yes very good idea. But you are looking at a tool with shipping 30 to 40 dollars which will only be needed one time for a home owner. You can buy a spark tester in this country from most any auto parts store for less then 5 dollars. For this 40 dollars will be able to tell how rich his engine is running which can be done by just looking at the spark plug for free. I would say just remove the coil and take it to a dealer, have it tested, and most dealer will test it for free if you need a coil you buy it from them. If he doesn't want to spend the 5 dollars for the plug tester just take one of his many used plugs and open the gap to 1/4 inch and test it like I told him, another free test. My guess here is this is just a home owner with very limited resources.


#13

I

ILENGINE

Be aware also that the certain briggs engines built after 2012 use a plug with a gap of .020 as opposed to the older engines that used .030, the wrong gap on the newer engines has been linked to a misfire.


#14

B

bertsmobile1

reynoldston said:
Yes very good idea. But you are looking at a tool with shipping 30 to 40 dollars which will only be needed one time for a home owner. You can buy a spark tester in this country from most any auto parts store for less then 5 dollars. For this 40 dollars will be able to tell how rich his engine is running which can be done by just looking at the spark plug for free. I would say just remove the coil and take it to a dealer, have it tested, and most dealer will test it for free if you need a coil you buy it from them. If he doesn't want to spend the 5 dollars for the plug tester just take one of his many used plugs and open the gap to 1/4 inch and test it like I told him, another free test. My guess here is this is just a home owner with very limited resources.
Click to expand...

No you are looking at a tool that will ship in a Royal Mail fixed rate small package for ｣ 6,00 worldwide just tha same as a USPS flat rate worldwide small packet.
I still use mine at least once a week and I have acquired the skill set / experience to read plugs that the OP has yet to master.


#15

reynoldston

reynoldston

bertsmobile1 said:
a Royal Mail fixed rate small package for ｣ 6,00 worldwide .
.
Click to expand...

Sorry I have no idea what you saying here. I got the price with shipping from E-Bay which is in dollars. Yes it looks like a nice idea and I see nothing wrong with it and the more ideas the better for the OP. If the OP wants to invest into such a tool it would be a good investment for him or a shop. I am just making a guess he is just a home owner and trying to fix this problem as cheap, fast, and easy as possible for a one time fix. Also it could be something different other then ignition like a tight valve. or other heat related things like too heat next to a fuel line.


#16

B

bertsmobile1

reynoldston said:
Sorry I have no idea what you saying here. I got the price with shipping from E-Bay which is in dollars. Yes it looks like a nice idea and I see nothing wrong with it and the more ideas the better for the OP. If the OP wants to invest into such a tool it would be a good investment for him or a shop. I am just making a guess he is just a home owner and trying to fix this problem as cheap, fast, and easy as possible for a one time fix. Also it could be something different other then ignition like a tight valve. or other heat related things like too heat next to a fuel line.
Click to expand...

Well actually the EVILBAY vendors want $ 47 + $ 22.95 P & P flat rate to anywhere in the USA ( world actually ) , a tad under $ 30 - $ 40.
Off Amazon they are $ 67.+ $ 11 P & P anywhere in the USA
And if you go to the Gunsons web site they will either post direct or send you to a local vendor which is generally cheaper.

Value for money depends upon how much the OP thinks their time is worth and how much he is willing to invest in parts that did not need to be replaced.


#17

J

jgaspelin

The mower has spark as I can mow my entire yard. Takes about 45 minutes. The engine runs smooth 10 seconds or so then sputters just a little. If cutting through thick grass the sputtering seems to stop. I took off the Kill wire and let the engine brake slow the engine down. No sputtering when the break was on a little.

Could coil still be going bad. I may just wait till it doesn't rune then take to a small engine repair place. Can't post video of it running or I would.


#18

J

jgaspelin

I may just wait till it gets worse to take to a mechanic


#19

B

bertsmobile1

follow the kill wire back to the coil.
If the roughness goes away when it is disconnected chances are there is a patch where the insulation is not good and the kill wire is making occasional shorts .


#20

ThaxtexGM

ThaxtexGM

jgaspelin said:
I have cleaned carburetor, changed spark plug, got new gas, and changed flywheel key and adjusted magneto spacing. The engine runs cuts entire lawn but sputters instead of running smoothly. I also put stabil in gas.
Click to expand...
hi jgaspelin make sure you put a copper core spark plug in it, all new NGK are, see how that goes.


#21

StrongHawk

StrongHawk

How about the choke setting, or the mechanical governor?


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