My ProMac850 is having issues. It idles and runs at low rpm just fine but when you give it full gas it begins to bog down and stall. Is this a fuel filter issue, carb issue, or some other problem?
I am no saw guru but I'd say it is your carb. If you just can't get it adjusted properly then try a carb rebuild kit first, that's the cheapest route. After you take the carb apart soak it in carb cleaner to try to loosen any gas that may be varnished in the ports. If that doesn't work then you may need a new carb. That's my opinion some people may know a better solution. Good luck!
I don't know that saw at all, but those symptoms sound like what can happen with a bad seal on the cylinder inlet port. Husqvarna 350 and 353 has a plastic snap as part of the boot assembly that fits over the inlet port. That loosens up, stretches, and the tight seal lost. If that turns out to be the case, it could be as simple as a $5 part and 30 minutes.
Sure sounds like a fuel problem more than likely carb related like blacksmith said. Also while you're in there check the simple stuff too, fuel line, fuel filter, carb adjustment H screw rattled in/out.
On an old workhorse like that, make sure all of the rubber is intact before you blame the carb. Fuel line (line leaks can make it hard to start too), tank vent, and other items should be checked before digging into the carb. Air leaks into the intake area or past the crank seals tend to present as idle problems as that is when the crankcase vacuum levels are higher. If your trouble is indeed in the carb, obtaining a rebuild kit is a wise and cheap choice. Those old diaphragms are usually stiff and/or stretched out of shape and will never function optimally even if you do get the carb squeaky clean.
Start it up, let it idle, pull throttle wide open and let it die, pull the plug out and post a picture of the plug.
MasterMech; I would think that if it were any of those issues then it wouldn't run at all. The last few times I have tried to use it, it works just fine for the first tank of fuel then bogs down on the second.
Welcome aboard Chris Herrmann Nice saw I believe with some of the advice offered, and any forthcoming, you'll be running that old beast right in no time. So what do you use that saw for? Cutting firewood to heat yer home? Do tell!
That swings the needle towards an ignition issue then. Heat builds up in the ignition coil assembly and can cause weak to no-spark conditions. Usually presents intermittently and gradually gets worse until the saw just doesn't run anymore. It is odd however that you are able to make it through a complete tank of fuel before the problem starts.
