GrumpyOldBastige 1 #1 Posted May 2, 2015 Elsewhere on the boards, I have documented my electrical problems with my '89 312-8 with the Kohler M12. I have those problems beaten, for the time being, at least. Thank God for the demystification guide- had wires out of place on the ignition switch. Anyway, new problem: Motor cranks over just fine. Verified fuel flow from tank, through filter, to pump, to carb. All ok. Pulled plug to inspect. Raw fuel on tip, definitely fouled; looked down plug hole, saw raw fuel there, too. I took the carb apart and cleaned what I easily could (did not do a 100% disassemble) Suspect issue lies with float/needle. Sidenotes- at the end of the last mowing season, the motor would cut out unless you popped the clutch and got moving, and I've had carb issues in the past. It's a Walbro WHG-52 carb. any and all input... Share this post Link to post Share on other sites
oldredrider 2,547 #2 Posted May 3, 2015 Do you have a spark at the plug? Seems like a silly question, but gotta have that to run. Try a new spark plug and see what happens. Start with the simple (cheap) stuff and eliminate them first. Share this post Link to post Share on other sites
GrumpyOldBastige 1 #3 Posted May 3, 2015 Do you have a spark at the plug? Seems like a silly question, but gotta have that to run. Try a new spark plug and see what happens. Start with the simple (cheap) stuff and eliminate them first. I haven't tested yet. Will grab a plug tomorrow and check for spark, then report back. I'm guessing I ruined the current plug (less than a year old) trying to start it anyway. Share this post Link to post Share on other sites
tommyg 152 #4 Posted May 3, 2015 You can try grounding the metal part of the plug on the engine and crank the engine over looking for a spark. My hunch is that you don't have a spark at all. While you're at it, double check all your connections to the coil. Might want to check your points gap as well. Share this post Link to post Share on other sites
Save Old Iron 1,563 #5 Posted May 3, 2015 (edited) The spark could be getting killed by safety interlocks. Check for a 5 pin electrical connector near the engine block. see diagram at the end of this post. If you unplug the connector, the kill wire for the magneto will not be disabled by any issues with ignition safety interlocks. If you crank the engine with a grounded spark plug, the mag should fire the plug. . Edited May 3, 2015 by Save Old Iron Share this post Link to post Share on other sites
GrumpyOldBastige 1 #6 Posted May 4, 2015 (edited) The spark could be getting killed by safety interlocks. Check for a 5 pin electrical connector near the engine block. see diagram at the end of this post. If you unplug the connector, the kill wire for the magneto will not be disabled by any issues with ignition safety interlocks. If you crank the engine with a grounded spark plug, the mag should fire the plug. . Got it to start by disconnecting that plug. Little did I know that the throttle cable would come undone, the ignition is useless when that harness is unplugged, and c) I almost blew it up by somehow bypassing the governor while trying to shut it off. I just held the throttle closed and gave it full choke. Needless to say I'm plugging that plug back in. Scared the holy bejeezus out of me. I should have just disconnected the coil wire but no, too easy. So- unplugged- passed spark test. Plugged- no spark. Now let's hope I didn't cook the rod bearing... What does this mean? Edited May 4, 2015 by GrumpyOldBastige Share this post Link to post Share on other sites
wallfish 15,985 #7 Posted May 4, 2015 First off, you should get the throttle and governor set and attached properly. Disconnecting that plug is the best way to test it and just applying choke will shut it down. If you disconnect the coil wire like you say, you still have the same situation since the key will not work with it like that either. The governor should've closed the throttle if the cable came loose and the engine should've automatically went to idle. You must have something hooked up wrong or out of adjustment with that if it took off on you. Something in your wiring is grounding the white wire which goes to the coil and is the magnito ground. The only pupose of that white wire coming from the engine is to shut it down. Take a multimeter and systematically go through your wires to find what is grounding that wire. Has this tractor been rewired? Share this post Link to post Share on other sites
GrumpyOldBastige 1 #8 Posted May 5, 2015 It was partially rewired last year. At the same time, the safety switches and the starter solenoid were replaced, but I don't believe they are the problems in this case. This problem is a new one, and did not make itself known at all last season. I bought a multimeter last month, but I'm still learning my way around electrical- very much a rookie. Pray tell, how do I test the wires? Share this post Link to post Share on other sites
wallfish 15,985 #9 Posted May 6, 2015 Set the meter to the symbol that's something like this -> | When you touch the leads together it will tone or beep Connect one lead to ground ( any steel on the tractor ) and the other lead to the pin in the connector (tractor side, not engine side) which connects to the white wire from the engine. When the key is turned to the "OFF" position, you should have continuity and hear tone. When the key is in the "RUN" position, there should be no tone (open circuit) Make sure the leads are connected securely so there's no accidental disconnect. Use small pieces of wire or alligator clips With the key in the run position, systematically check your wiring to find the problem. The tone should stop. Refer to the electrical diagram for your tractor so you can check EVERYTHING. I'd pull the connector to the key switch first to eliminate a bad switch , then go to the safety switches. Share this post Link to post Share on other sites
gwest_ca-(File Mod) 10,533 #10 Posted May 6, 2015 A few pages from the electrical bible Demystification Guide How to use a multimeter Garry Share this post Link to post Share on other sites
