Well, we finally got some real snow here on the east coast, so that meant some rare action for the snowblower. This is our fourth winter with the snowblower, and it’s getting more and more tempermental with each passing year. It’s getting harder and harder to start, and it’s developed this habit of quitting on me before I finish clearing the whole driveway. It will always start back up, but then I have to kind of nurse it along the rest of the way. Now, this is one of those problems that tends to get forgotten, because I eventually do get the driveway cleared with it, and then it gets put away, then spring comes, and it sits all summer, and then it has the same problem the next winter. It’s just the way things go with equipment that doesn’t get used much.
Anyhow, I decided things would be different this winter, and I would make at least a halfhearted attempt to identify and fix the problem. So, after the usual routine of: Clear 90% of the driveway, restart snowblower after it quits, nurse snowblower through remaining 10% of driveway, I set to work. The best thing to do with engine problems is to apply the scientific method, ruling out as many things as possible, until you find the problem. So here goes:
Fuel cap venting issue: This was the first thing I suspected. Sometimes I can get it to start, or keep it from stalling, by loosening the fuel cap. If the fuel cap doesn’t vent properly, it can cause a vacuum that prevents fuel from getting to the carburetor. I haven’t totally ruled this out yet, but there doesn’t appear to be anything wrong with the fuel cap. I’ve read that they vent through the threads, and there’s a plastic standoff in the cap that keeps it from sealing tightly against the lip. This all appears to be intact and functioning properly.
Carb out of adjustment: The engine has always run a little lean, requiring me to partially choke it sometimes to keep it from missing. So I figured, maybe I need to tweak the fuel mixture. Well, it turns out I have a bogus low-emissions carb, with non-adjustable jets. So much for that idea.
Main jet gummed up: I drained the float bowl, unscrewed the main jet/emulsion tube, and blasted it with carb cleaner. It did look like there was a little bit of gunk in there. I should probably do this every spring. But unfortunately, this didn’t solve the problem.
Out of gas: Seems obvious, but there appeared to be plenty of gas still in the tank. However, I topped the tank back up, and it seemed to run OK again (well, “OK” with this engine is a very relative term). Apparently the fuel pickup tube (or whatever mechanism it uses) doesn’t go all the way to the bottom of the tank.
I think the next step is to examine the fuel tank, fuel line etc. to see if there is anything that could keep fuel from reaching the carb properly. I’ll do that at the end of this season. Once I’ve ruled that out, if I still have problems next season, I’ll break down and overhaul the carb. Eventually, I’ll get to the bottom of this.