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Riding lawn mower engine surges.

14 years ago

My riding lawn mower all of a sudden just started surging. The person I got it from told me it had been surging before. When I got I cleaned the combustion chamber and i also took of the muffler and the carb (but didn't clean them). When I put them back on I started the engine and it was running fine. I started it at least once a day and drove it around. I don't have the deck installed. Yesterday I installed put on the air filter (until now i had been using it without an air filter)and i drove it for about 40 minutes and then all of a sudden it started surging. It surges a lot when i have the throttle at minimum. But the surging almost stops when i pull out the choke. When i look into the carb there is a little jet from which gas squirts out at intervals.

Engine: 18 HP Twin Cylinder Briggs and Stratton

Model: 422707 Type: 151001 Code: 92061212

Mower: Signature (by MTD) 2000 Elite

Thanks

Featured Answer

kossio95
Original Author

14 years ago

I cleaned the carb very well (I think). And I flushed the fuel lines. About what rcmoser suggested i cleaned the fuel tank when i got the mower ( about 1 month ago). Today I started the lawn mower and it ran fine for a few seconds than I put the throttle at min. and it started surging again. When I put the throttle at max. the surging to slowed down. Right now the engine still surges but it is not as frequent.
Thanks

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Comments (11)

tomplum
14 years ago
You will need to service the carb. I do these right on the machine. Pull the air filter assy, clean off the outside of the carb body- then remove the 4 screws that hold the top of the carb and then the top. You can remove the drain and clean everything out w/ carb spray cleaning all the passages in the top and bottom. The spray will shoot back at you at times so be cautious and wear goggles. You will have to replace the body gasket only if it tears. Remove the fuel filter , flushing fresh fuel through the lines completely and then replace the filter. That ensures all fuel is fresh going into your freshly cleaned carb...
rcmoser
14 years ago
In addition to tomplums great advice I would also remove the gas tank and clean it out if you machine is a few years old. You maybe susprised whats laying at the bottom where the fuel pick up is. And if this machine is over 7 years old I would personnal change the fuel lines. That way I will not have to worry about a fuel contamination problem for quite awhile unless something unusual happens like fueling it with contaminated gas or letting it set for a long period of time with todays gas in it.
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walt2002
14 years ago
Still fuel starvation sounds like. When you had the top off the carb, did you probe the brass looking orifice looking up at you in the top of the carb body. Use "tag" wire of something similar.

Also check vacuum line running from the engine block to the bottom of the fuel pump on carb. for leaks. Fuel pump its self may not be working properly.

Walt Conner
walt2002
14 years ago
Forgot to add, IF you don't find anything, might try Seafoam in the fuel per instructions on the can.

Walt Conner
kossio95
Original Author
14 years ago
I also noticed that when I put the mower in gear and it starts moving the surging stops. Anyone know why this happens.
Thanks
kossio95
Original Author
14 years ago
There is small brass tube. Its end is cut of at an angle and the tube is tilted upwards but the opening is pointing downwards. Is the the brass looking orifice that i am supposed to probe with a wire?
Thanks
spiceybones
14 years ago
Hey, I am having the same surging. After reading the post for carb rebuild, I am now more familiar with why this is occuring. See optional link.

Here is a link that might be useful: Need carb rebuild kit for JD L111
kossio95
Original Author
14 years ago
I opened the carb again and soaked it in hot water and dish washing detergent. Then cleaned all the jets and ports with compressed air. When I put it back and started the engine there was no surging. Got it fixed.
Thanks to everyone.
austin425e
6 years ago
I have the same problem with mine and it has a new carb and newish fuel pump any ideas on how to fix?
espears1
6 years ago
Just moved the right hand spark plug wire away from all the pipes. Runs like it's brand new!! :)

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