|Dave Mertz in MI ||
Posted 09-16-2003 at 21:54:57
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A couple days ago I posted a message about my McCulloch chainsaw (Timber Bear, 20" bar, early 90s model) that I've been having trouble with.
I don't know what's wrong with it, but I've got some ideas, and I've got a better handle on what it's actually doing. The trouble with it flooding was actually my own doing. I realized that I was priming it too generously. *d'oh*
What the problem seems to be is a lack of enough fuel to the engine, or perhaps an air leak.
I can get it to sputter with a little prime or ether, and after quite a bit of that, it will reluctantly begin to run. It seems to get some fuel, fire up, but then when that little burst of fuel is burned up, the engine cuts out, then it gets some more fuel in there, fires up again, burns it all, cuts out, fires up, cuts out, and fires up, until finally it is running smoothly.
Maybe it is a problem with the fuel pump, or a leaking gasket in the carb, or something else.
I think I've ruled out an air leak in the fuel line, because I troubleshot it today by hooking a different fuel hose up to it and running it to another tank of gas, and the engine seemed to behave the same way.
The mixture screws aren't the cause either. I've got them pretty well adjusted.
Something interesting is that if it's warmed up, and I shut it off, it'll usually start up again, no prime, no problem. But, if I run it out of gas, refill it, and try to restart it with a hot engine, it's impossible. Even with priming.
See, if it were a problem with not enough gas actually getting into the engine (a bad pump or fuel line or something), shouldn't priming allow it to at least fire a little bit here? But if there's some sort of a bad gasket in there or something, that allows too much air into the system, maybe that could be the cause of too lean of a mixture, even with priming it hot, maybe?
Chainsaws frequently drip some oil out of them after use right? Well, this one seems to leak large quantities of what seems to be 2-cycle oil, not chain oil, from the engine area. Could this be a sign of a leaking gasket where the cylinder connects to the crankcase? I'd suppose that air getting in there would cause these problems, right?
What do any of you guys think? Am I right?
|Gary, Mt. Hermon, La ||
Posted 09-17-2003 at 06:06:42
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Dave, been there, done that, rebuilt the carb, new needle valves, gaskets, new plug, new gas tube to carb, new gas line filter in the tank, removed the gas tank drained it blew it out with compressed air, put fresh gas mix, still the same situation as you. I even looked real hard at the coil and the gap for the magneto, but I got spark so didnt think more about it finally I quit and bought a new one of a different brand.