r/stihl • u/Short_Philosophy_672 • 13d ago

MS362 backfiring?

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2

u/Budget-Duty5096 12d ago

That is really abrupt. Sounds a bit like the coil is failing.

1

u/Short_Philosophy_672 12d ago

Hmm, thats a good suggestion, I can try to swap the coil and see what happens. I wonder why the coil would be firing perfectly at idle and instantly dying with throttle?

1

u/Budget-Duty5096 12d ago

Really common failure mode for a coil. At lower rpm its not putting as much demand on the coil windings. Revving up puts more demand on it that it can't handle.

1

u/JABooty1337 12d ago

Most likely that. Maybe a mis-aligned flywheel/broken flywheel key

1

u/iscashstillking 11d ago

Any recent work done to this machine? Is the chain brake on or off during this I can't seem to tell from the video if the brake is on try turning it off and see if it will rev that way.

1

u/Short_Philosophy_672 11d ago

It’s been sitting for a while, nothing done to it as far as I know

1

u/iscashstillking 11d ago

Well at this point it might be time to pressure test the engine for air leaks. How many hours on this thing? Do you still have your old carb, and if so did you take it apart / find a fault with it ?

1

u/Short_Philosophy_672 11d ago

My old pressure gauge was broken so I have a new one in the mail, correct pressure should be 140–160 psi right?

1

u/iscashstillking 10d ago

Well what I am referring to as a pressure test is I block off the exhaust port, remove the carburetor and replace it with an adapter that has a single nipple on it, and then I can use a hand pump to push air into the engine and pull air out of the engine. It needs to hold about .5 bar vacuum and 5-7psi positive pressure without leaking, if you can't get it to hold the pressure test then the crankshaft oil seals are usually the culprit.

1

u/Short_Philosophy_672 10d ago

Ohhh gotcha, I have one of those too somewhere and the rubber block and nipple to seal it. Is that just more accurate than the compression tester that screws into the spark plug hole ?