Craftsman 42 cc shainsaw runs great wide open, but will not idle

[etbrown4]

We have very thoroughly cleaned the carb, and replaced the fuel lines. The gas filter is clear.

We have tried the L and H screws everywhere from 1 full turn out, to 4 turns out with little effect.

(Both the L and H screws were initially at 1 3/4 turns out.)

Suggestions appreciated.

 

[FlyingDutchman]

does it just die or does it sit there and scream instead of idling? My saw has an idle adjustment screw... but i have had engine and carb gasket to engine leaks that caused both problems

 

[etbrown4]

it dies as soon as you release the throttle

 

[Chris-PA]

Will it keep running if you give it some choke?

 

[XFR_Jay]

compression?  Bad seals or gaskets?

 

[o8f150]

since i have done many of those i will add my 2 cents,,,, rebuild the carb and replace fuel lines,, those saws are bad about that

 

[CTYank]

No mention of idle throttle setting. Give it a few turns clockwise, and try again. Repeat a few times.

Watch for moving chain. :msp_smile:

No joy? Carb cleaner and gentle compressed air where the L needle was, on temporarily removing same.

All else fails? Carbs aren't that expensive.

 

[Edge & Engine]

You have an air leak somewhere. Those saws are notorious for developing a major leak between the carb manifold/block and the engine. Make sure the screws that hold the manifold on are tight. (If they aren't, don't just tighten them up and run it...if the screws are loose the gasket is almost surely damaged). If it's not leaking there, you might have a bad crank seal...ideally you would pressure test the crankcase.

 

[Chris-PA]

You have an air leak somewhere. Those saws are notorious for developing a major leak between the carb manifold/block and the engine. Make sure the screws that hold the manifold on are tight. (If they aren't, don't just tighten them up and run it...if the screws are loose the gasket is almost surely damaged). If it's not leaking there, you might have a bad crank seal...ideally you would pressure test the crankcase.

Never ran across that - the design is straight forward, but of course if the gasket gets damaged it will leak. I was trying to figure out if it had an air leak or if the idle circuit just wasn't working.

 

[2lungs]

No mention of idle throttle setting. Give it a few turns clockwise, and try again. Repeat a few times.

Watch for moving chain. :msp_smile:

I just received a craftsman that was doing the same thing. The idle stop screw was missing! Put one in and idles fine.

 

[dswensen]

Make sure the screws that hold the manifold on are tight.

But not TOO tight or the plastic manifold will crack - don't ask me how I know.