Engine Surge Problem


Old 05-21-02, 06:45 AM
Small Shop
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Engine Surge Problem

I am working on my neighbors lawnmower, Sears model number 917.377641. The engine is Model number 143.986516 but I do not have a service manual to convert this number to Tecumseh numbers.

The problem is the engine surges after starting and the only way to get it to smooth out is by pressing the primer bulb when it starts to die. Doing this for about the first 15 seconds cures the problem and it will run fine from then on. The original problem was failing to start and troubleshooting revealed a small amount of brackish, brown water in the tank. I've cleaned the tank, removed the carbuerator (plastic) and cleaned it also. No mixture needles to adjust or anything. Put it all back together and ended up with this surging problem. Haven't troubleshot the mechanical governor yet.............possibly a bad spring maybe ???

Tom? Cheese? What do you think? Wish I had a manual to cover this particular carb but the best I can do is a parts breakdown at Sears parts direct. Plastic carb is $54..........OUCH !! My lack of experience with THIS carb is stumping me !!!!

Thanks, Steve
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Old 05-21-02, 07:24 AM
Join Date: Jul 2001
Location: Riverdale, MD
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Take the screw holding the carb out again and check the holes that are in it. They have to be cleared out. If you happen to have a set of welding tip cleaners, use them. The inside of the screw may need cleaning out also.
Old 05-21-02, 02:07 PM
Small Shop
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Found the problem ! When I had put the carb back on I accidently routed the governor rod over the spring causing it to bind. I also found a manual that covers this specific model of carbuerator so the governor section showed how it was to be hooked up.
Runs fine now and no more surging. Live and learn I say !!!!

Thanks for being available to help guys !!!

Old 05-21-02, 02:13 PM
Small Shop
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Thanks for the response but I think you are thinking of a different carbuerator. Not sure what you meant but think you were talking about the nozzle that holds the float bowl onto the carb body ???
I agree about the small holes being plugged. Have seen this on others and it really can cause problems.

Again, thanks for the reply.............Steve
Old 05-21-02, 07:30 PM
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Hello: Steve

Glad you found and corrected the problem. Thanks also for posting back the problem description and it's correction.

Thank's also for reminding me to mention an important point. Make a hand drawing on paper prior to removal of any part with which you have never removed before, any part that has multiple pieces attached to it or is an assembly of parts.

Crossing up the throttle linkage and the govenor linkages at the carb is an all too often made error. Happens to everyone at one time or another, DIYer's and pro's alike.

Regards, Small Engine Forum Moderator
Tom_Bart.....TCB4U2B2B.....Company Enterprises.
"Accurate Power Equipment Company"
Small Engine Diagnostics Services and Repair.
Old 05-21-02, 08:24 PM
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Thanks for the tip on the drawing Tom. I do this with most tecumseh engines and their linkages and just this week started using a digital camera. I just got the camera recently and have found numerous uses for it other than just normal photography.

Old 05-21-02, 08:40 PM
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Hey! That's a great idea Steve! I really dislike those new techumseh plastic carbs, especially on the larger riding mower engines. Talk about disposable products....sheesh! They could at least use bakalite (spelling?) or something similar that won't turn to mush in a chemical dip so we could clean them right.

Glad you got it going!

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