I bought a Troy Bilt chipper/shredder from a friend; it's got a 5 hp Tecumseh engine. He bought it, ran it a few times and discovered he really didn't have that much to be chipped/shredded; he estimates about 12-15 hours run time, tops. He drained the gas and stored it in his barn, unused, for about three years. I figured there'd be a little restoration work involved in getting it running again, although he said it was running fine last time he used it.
I got it home and sprayed some ether into the carb; it started right up but ran hesitantly, with light puffs of black smoke coming from the muffler. I took the carb off, disassembled it, and cleaned off the gum deposits from all of the surfaces and channels where the gas travels.
On restart, it ran smoothly for a while and chipped some branches. I shut it down and tried again a little later, at which point it started the puffing and low power again. I once again disassembled and cleaned the carb but it wouldn't run strong again. It's obviously getting too much gas, running rich. When I adjust the needle valve in the float bowl, it runs better as I tighten it down but it seems like it needs to go another half-turn past full stop to run right. I did clean the tip of the needle valve so the problem isn't gum on the point preventing full closure.
The engine has good compression from the resistance to the pull cord and it has fresh oil in the crankcase. My thought is that there are gum deposits in the carb in places I can't see or reach; I'm going to put some carb cleaner in the tank and just let it puff along for a while without load to see if that cleans it.
Any other suggestions would be appreciated.
Paul