TC10284 111 #1 Posted September 6 (edited) p220g on a 520HC. Did run late last year but surged badly. Finally got around to messing with it. Cleaned carb. No start. Dumping a bit of gas directly into the carb and no start. Compression on both cylinders is good - almost 120PSI on both. Tested for spark with spark tester and got nothing. Even stuck spark tester directly into the coil plug hole and still nothing. Swapped plugs with known good plugs - no start/no spark. Checked coil with the test in the manual. Ohm readings were in spec. Then I tried the timing check and that's where I ran into something interesting. I connect the negative lead of my voltmeter to the negative of the coil and the positive of the voltmeter to a good ground as stated in the service manual. Turn ignition switch to Run. See 0.87v on voltmeter. Rotate the flywheel by hand clockwise as it states in the service manual, it never changes off 0.87v, where it's supposed to show the battery voltage. It's like the Ignition Control Module is stuck. I also never hear a "click" like I've heard before when checking timing on a P220g and the voltage is supposed to change. Am I looking at a new Ignition Control Module? Or maybe a magnet is stuck on the ICM? Edited September 6 by TC10284 Share this post Link to post Share on other sites
lynnmor 7,305 #2 Posted September 7 Sounds like you followed the tests in this thread: https://www.wheelhorseforum.com/topic/50487-my-onan-doesnt-have-spark/ If you did the module is suspect. 1 Share this post Link to post Share on other sites
TC10284 111 #3 Posted September 7 (edited) 14 minutes ago, lynnmor said: Sounds like you followed the tests in this thread: https://www.wheelhorseforum.com/topic/50487-my-onan-doesnt-have-spark/ If you did the module is suspect. Yes except for connecting a test lead from battery positive to coil positive and trying to crank it and look for spark. It makes me wonder if it's not an ignition switch problem. The oil level is not low, but I guess could still be causing a problem. The constant 0.87v instead of battery voltage when testing the timing is concerning though. And yes, I hate to have to buy another ICM. Edited September 7 by TC10284 Share this post Link to post Share on other sites
Streetrodchev 798 #4 Posted September 7 Sounding like either the ignition module or the hub with the magnets. Time to pull the flywheel off. Share this post Link to post Share on other sites
lynnmor 7,305 #5 Posted September 7 11 hours ago, TC10284 said: Yes except for connecting a test lead from battery positive to coil positive and trying to crank it and look for spark. It makes me wonder if it's not an ignition switch problem. The oil level is not low, but I guess could still be causing a problem. The constant 0.87v instead of battery voltage when testing the timing is concerning though. And yes, I hate to have to buy another ICM. Do the "connecting a test lead from battery positive to coil positive and trying to crank it and look for spark." There is NO LOW OIL LEVEL SWITCH. This idea comes up from time to time. The oil PRESSURE switch turns on the oil pressure light when there is no pressure, once running the oil pressure switch turns on the hour meter. That is all it does. 2 Share this post Link to post Share on other sites
TC10284 111 #6 Posted September 7 When connecting a jumper lead from battery positive to coil positive, I get appropriate spark with spark tester when turning key to Start. When I remove the jumper and turn key to Start, the spark tester either shows no spark or will show constant spark on the spark tester. Constant, meaning it stays lit up the whole time I hold the key to Start with no flash at all. Share this post Link to post Share on other sites
TC10284 111 #7 Posted September 7 Replacing the ignition switch cleared the problem. This is why I keep spare key switches on hand. Geez. 1 Share this post Link to post Share on other sites
