Briggs & Stratton vanguard motor (mod#350777-1142E1). I rebuilt the carb and replaced spark plugs and the motor runs good but "diesels" and backfires thru carb when the ignition is turned off. It seems to be running rich and spits black smoke while "dieseling". Is ther any way to lean out the carb micture?
rebuilt carb and changed spark plugs and reset gap -coils to flywheel - to 0.015.
Hello, and thank you for choosing JustAnswer. I'll be helping you today and am committed to providing clear and concise answers to your question.
First, let's get the air gap within spec. It should be .008" -.012", so shoot for .010".
Does it still backfire at the correct setting? Have you checked the flywheel key yet?
Saturday the engine would not run and backfired throught the carb while cranking. I pulled the flywheel (the key is good). The air gap was at 0.010 and I reset it to 0.015 in an attempt to retard the spark.. This seemed to fix the problem - I ran the engine and it ran fine but appeared to run rich. I turned the key off and it continued to "diesel".
My previous note stated it dieseled and "backfired" through the carb but that was not a good description - the ignition was off and it was dieseling and spitting thru carb.
It looks to me like the mixture is way too rich. ? ?
That's a fixed main jet, so it cannot be a mixture adjustment issue, but have you checked the needle and seat to be sure you your bowl is not overfilling? That will cause the spitting your describe and really mess up the mixture.
This story is getting complicated. I checked float needle and reset it as you suggested and the mixture leaned out and the motor runs like a top. BUT the "dieseling" I described (with the ignition turned off) is not due to dieseling. It is due to one spark plug continuing to fire with the ignition off . With the ignition off and the motor "running", I pulled off the right plug wire - no affect. I pulled off the left wire and the engine died immediately.
So the left spark plug continues to fires with the ignition turned off and the flywheel turning. Any suggestions? Is this a coil problem or a wiring problem?
Check the small ground wire at the base of the ignition coil that's still firing. Chances are that it's disconnected of damaged. This wire is what grounds out the ignition when the key is in the off position.
Outdoor Power Equipment technical trainer since 1990, covering eight states.
the wire was rubbed and broken
Glad to hear the problems are resolved! Thank you for the accept, and best of success in all your hands touch...