Old Tecumseh - High Speed Keeps Changing - Snowblower Forum : Snow Blower Forums
 
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post #1 of 4 Old 03-02-2019, 04:13 PM Thread Starter
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Old Tecumseh - High Speed Keeps Changing

A 1990 sidevalve Tecumseh powered snowblower. Did some extensive maintenance with summer (valves, cleaned combustion chamber, re-attached governor rod and new spring). This winter, the high speed keeps changing. I'll set it w the high speed screw, it'll be ok for 10 yds of driveway, and then it'll start running too fast. So I reset the screw, but then 10 yds later it's running too slow and weak.


I don't think the hi-speed screw is changing, but the engine won't be consistent.


Any ideas?

Joe
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post #2 of 4 Old 03-02-2019, 04:31 PM
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Sounds like a governor issue, wrong spring, wrong hole, not adjusted correctly.

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Is anything in the governor linkage sticking? On my OHV Tecumseh, there's a plastic bushing at one pivot which must be installed facing a certain direction.

Is the carb adjustable? I think I've heard that if the needle tip gets damaged (like from over-tightening the screw), it can be difficult to maintain a consistent mixture. Perhaps that could show up as changing RPM?

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post #4 of 4 Old 03-02-2019, 06:02 PM Thread Starter
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JLawrence, the engine is very sensitive; i.e. it will run well only with the spring on a particular hole, and the carb adjusted "just so." As you said, it's possible that the spring is stretched out or deformed from the years of taking off-on. It looks used and abused.


October, I don't think the gov lever is sticking, but I like your idea re the carb needle. I think I heard somewhere that a missing needle O-ring can cause this symptom, and I'm sure the engine's original needle O-rings are either missing or in bad shape.


I am going to follow the advice of both of you, and get a new gov link spring and new carb idle and main needle O-rings. I don't know if it will solve the problem, but these parts are needed nonetheless.

Thank you for suggesting them.
Joe
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