Engine hunting


Old 09-06-04, 06:35 PM
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Location: Montevallo, Alabama
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Engine hunting

Could someone please list the causes for engine hunting? This seems to be a real problem that I see a lot of. But aren't there multiple causes. Hit and miss cures can be very time consuming.
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Old 09-07-04, 09:31 AM
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It is hard to state a common cause for so many different engine types but I can tell you some that I have ran accross and read of in manuals.
Usually I find the fuel/air mixture is not set correctly.(A lean mixture can be a cause) On carbs that are adjustable, the factory recomended setting is a starting point and usually will have it close enuff but each engine is a bit different and each will usually have a sweet spot just off the initial setting. Surging at low speeds can be solved alot of the time by simply increasing the idle speed. A number of things can effect fuel/air mixture, leaks or blockage be it to air or fuel.
Another common cause I have seen is the linkage and springs for the carb/govenor either being installed incorrectly(some just modified during the installation most likely due to incorrect installation procedure, hence a need to bend or modify)
The govenor is the component that is responsible for maintaining a constant RPM as the load on the engine changes, however at least in my findings, the govenor itself is usually not the problem.
Page 26 of this manual http://www.cpdonline.com/692509.pdf gives some theory and checks for govenor suspected problems. It is for Tecumseh but the theory can be applied to most other small engines as well with similar govenors.
Old 09-07-04, 03:10 PM
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What application is the engine on?
Old 09-07-04, 05:07 PM
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Originally Posted by puey61
What application is the engine on?
It's off of a sears walk/behind lawn mower with an engine no. of 143.996004 which crosses to a LEV 115 tecumseh. It has a governer that I've never ran into before. The governor seems to be "pushed " onto the governor shaft and held in position by spring steel. It has the governor lever held by a screw off to the side. The part that's pushed onto the shaft seems loose. It's really hard to tell because the shaft doesn't turn much.
Old 09-08-04, 12:10 AM
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Hunting is alost always caused by a lean fuel ratio (partially clogged or misadjusted carb or air leak).

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