screech 16 #1 Posted July 8 My 312-8 does not shut off when the ignition switch is turned off. I throttle down to an idle , turn off the ignition and it sits there and runs,,,,UNTIL I give it some gas and it putters and backfires with a big BOOM and shuts off. What could be the problem? Thank You! 1 Share this post Link to post Share on other sites
ebinmaine 67,766 #2 Posted July 8 That's probably a Magneto engine and it requires a ground to shut off. You've probably lost ground connection to the ignition switch or, you have a bad ignition switch. Does the backfiring occur at any other time? 4 1 Share this post Link to post Share on other sites
ebinmaine 67,766 #3 Posted July 8 Until you get the problem figured out you could also just use the choke to kill the engine. Idle it down as you've been doing. Pull the choke. Engine should die. Does the battery stay engaged? Do you have an hour meter that stays on? 2 Share this post Link to post Share on other sites
adsm08 2,103 #4 Posted July 8 @ebinmaine is most likely correct. My dad's did this a few years back and the wire from the ignition switch to ground the ignition out had broken. I'd find that and check it out. 3 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,070 #5 Posted July 9 Try lifting your a$$ off the seat with the mower engaged. The engine should shut off and the seat light comes on to tell you what you did or that the pto is engaged. 2 1 Share this post Link to post Share on other sites
Ed Kennell 38,329 #6 Posted July 10 Pull the head and decarbon. 1 Share this post Link to post Share on other sites
pfrederi 17,743 #7 Posted July 15 Quick test.. take the small wire off the solenoid. If starter stops spinning then the issue is in the ignition switch (or wire from it to solenoid). If it keeps spinning buy a new solenoid 2 Share this post Link to post Share on other sites
