Small Engine Repair Question
 

I have a Tecumseh 4 stroke snowthrower for the past 4 years. I recently did an oil change and spark plug replacement on it, and now the engine will not run when the choke is released, even when properly warmed up. The only thing different about this motor is the spark plug. Is this the culprit, or is there something else I should check. The manual doesn't provide an answer, it just says to call a dealer.

Thanks.

Probably a gummed up or varnished carb. Is it a floatbowl or diaphragm carb?

The older techumsehs had adjustable needle valves for the main jet and the idle jet, the later "fixed" ones usually need a good disassembly and cleaning, brake parts cleaner works well.

carb is probably plugged up. stall gas or dirt.might try some gas additives but most likely needs cleaned and possible diaphrams/gaskets

could also be areally dirty air filter

if it's a Floater type carb, take the bowl off, Rinse out all the old gas with a little new, Also a thing to check is the hole though the bolt if there's one. I fixed a power washer from goodwill by cleaning out the jet in there, Runs like a champ now. A multitude of problems can be fixed just in the carb... as an after thought... did you check the gap on the plug? it might not make a huge difference... but I'd still check it to be sure.

Thanks for the suggestions. I'm not sure what kind of carb it is, but the engine itself is only 4 years old. I'm not even sure it has an air filter. I'll check for that and run some carb cleaner through it to see if that helps. If not, I'll have the carb cleaned out.

Get friendly with your local dentist and hit him up for some used root canal files- they're great for cleaning small carburetors. The bolt that retains the float bowl is the main jet assembly- it will have an orifice in the bottom and possibly another very small hole at a 45 degree angle just above the lower set of threads. Once they're both clean, you should be OK.

I've got that engine on my snow blower. It doesn't have an air filter to plug up. The carb is very simple- I use a reamer from my welding torch cleaner set, which can be bought easier than a root canal file. A good blast of carb cleaner or brakekleen will help.

A word of warning about brake cleaner.
Do NOT ever use brake cleaner around heat. When heated, brake cleaner, unlike carb cleaner, will emit phosgene gas. Nasty stuff.
Spraying some on a hot engine may hit the exhaust and make just enough of that deadly gas to be bad news.
I read a safety tip from someone who used it instead of carb cleaner for a pre-welding cleaner. Some brake cleaner remained in one of the rust pits. When the guy hit it with the torch, it vaporized and he inhaled enough to nearly kill him.

Thanks for the warning. I'll stick with carb cleaner then.

Can you give her a small shot of starting fluid to see if that'll get it running long enough to get gas moving through the carb? My leaf vacuum required this ritual each fall (if i forget to add Stabil to the gas tank when I store it the year prior). Usually a quick shot of fluid near the air intake will do the trick.

Chas H's suggestion is good, however, the smallest tip cleaner is too big to clean the idle jet. Dentists only use RCT files one time, and then they're discarded- they cost about $15 each in case you wondered why RCT is so expensive. I got 20 or 30 from my dentist once- all I had to do was ask, but then again, I'm a good customer.

Try another plug. I had that same thing happen to me and it turned out that when the old plug was used, it worked. Another new plug and it worked. That one plug, no deal.

I think we have a very similar snowblower. First my dad was having trouble because the car float was stuck, but that was with gasoline going everywhere, so you'd notice that. Second was, my mom couldn't start, no matter what you did. MAKE SURE YOU HAVE THE KEY IN. I sat there trying to figure it out, and took out the plug to make sure it was getting a spark and I saw the key on the floor.

The key is in, and the motor will start and run on both the full choke and partial choke settings. It dies as soon as I turn the choke off, even after sufficently warm.

I will try the carb cleaner this weekend when it warms up a little bit. Failing that, I'll try a new plug as it was the only thing that changed with the engine between April and November. I drain the gas when I store it for the year, and always make a point of running the carb dry of gasoline before storing it.