036 tuning problem

[Butch(OH)]

My trusted 036 has a tuning problem that has steadily gotten worse over time and has me stumped. Can adjust idle and high speed to make the saw run and idle great. But sometimes have to reajust it next time it gets run, say a week later. Might be too lean, might be too rich can't make ryme nor reason of it. The same time all this started the throttle needs to be blipped a couple times to keep it from dying afer a long cut, then it will idle fine and will sit and idle forever as far as I can tell. The idle problem does not exist the first cut or two but gets worse as it warms completly to operating temp. Here is what I have done so far. Checked the fuel filter in the tank,looks OK, cleaned the tank vent, replaced the plug (twice) and washed the air filter. Tightened the intake boot and checked it and the lines for cracks etc. Problem has continued over several different cans of fuel mix. Been using Alky blend fuel because that is all we can get here. The pulse line and fuel lines look OK but I have no way to check them. Saw has about 200 hours on it Im guessing, any suggestions?

 

[West Texas]

Dumb as it may sound, I had what appeared to be the same problem on an 036 Pro. After working on it for several days, solved it by setting the LA idle higher. Instead of being set at about 2800 rpm I set it at 3000 rpm and have not had a problem since; and, the chain does not run at that rpm, at least not on this saw. Probably not the 'school' solution, but it worked.

 

[Lakeside53]

unfortunately the only way to really isolate the problem is to pressure AND vac test the saw. If you can't, your local saw shop can. It can take a while to set up and after wards, to reinstall the carb and muffler, but it will remove any doubts.

If I was to guess, it will be the oil seal under the flywheel. They start to fail under vacuum gving unstable idle, and you "fix" this by increasing the idle mixture to compensate, but sometimes the saw is then to rich to idle after you run it hard, so you increase the idle speed, and....... Chasing this around is a pain as it slowly gets worse, not better.

 

[046]

besides checking for vac leaks. blended fuel has been know to desolve diaframs in carbs.