Stihl MS 310 chain saw problem, won't run

Hello everyone, With the cold weather this is very bad timing but we are really hitting the wall trying to figure out why our chain saw suddenly stopped. It was starting, then die within 3-4 minutes, now no start at all since Bob took the carb. apart to clean it thinking this was the running problem. Now it won't start unless using spray starting fluid ... for 3 sec. The air filter has been cleaned, fuel filter looks clean & seems to be flowing but Bob wonders if there is a check valve in it. He can't see how to check the fuel lines without taking the entire saw apart which at this point seems like a bad idea. It leaks fuel slightly if turned on it's side as if to fill, which it wasn't doing before and happens when he takes the fuel filter off - that doesn't make sense to him either. He has searched thru the entries here and gone thru every suggestion, so we need some good brainstorming here.

 

The problem could be in the cap to the fuel tank. The vent in it could be plugged or faulty or the diaphragm in the carb that does the fuel pumping may have been due for replacement.

However, at the point you are now with the carb problems in leaking and having been disassembled, I would get a kit for it. They aren't too bad to put in and not overly expensive.

I wouldn't keep starting it on starting fluid until you have the carb in good shape.