TC10284 121 #1 Posted 16 hours ago (edited) 520H 4120oe02 1032657 with p220g. Earlier this year in spring, I mowed with this tractor. It suddenly would start sputtering and die after 20 or 30min unless I did full choke. It would run again for a bit after cooling down and do the same behavior. Replaced fuel, cleaned carb. Same behavior... OK, so that told me there was a possible issue with the ignition control module. So I swapped it. Swapped the rotor also. I can get spark with a spark tester, but I see NOTHING on the spark plug (ngk tr5). I just tried a totally new ngk tr5 plug and still get the same results. Spark in the tester but not on the plug. I've tried jumping from battery positive to coil Positive. Same results. I dump some gas in the carb and I get nothing. No backfire, not a puff, not even trying to fire. Battery is good. I've even tried a booster on it. Flywheel Magnets are not stuck to the stator. New coil. New condensor. Compression on both cylinders good. Even replaced the ignition switch. I am currently at a loss. Edited 16 hours ago by TC10284 Share this post Link to post Share on other sites
pfrederi 21,091 #2 Posted 16 hours ago What kind of spark tester are you using. The Harbor freight neon bulb type will often flash yet there is insufficient juice to fire the plug. B&S type will give a better picture of strength. Share this post Link to post Share on other sites
TC10284 121 #3 Posted 16 hours ago (edited) The harbor freight kind, yes. Also, sometimes I see an initial Spark on the plug when I turn key to Start and then nothing, and then one when I go from Start to run, or sometimes run to off. Edited 16 hours ago by TC10284 Share this post Link to post Share on other sites
Wild Bill 633 938 #4 Posted 15 hours ago (edited) 1 hour ago, TC10284 said: The harbor freight kind, yes. FYI, the Chinese always give you more than you expect. Like their carbs come with extra machining chips and they need to be deburred. Maybe they added spark to their spark tester. Edited 15 hours ago by Wild Bill 633 1 Share this post Link to post Share on other sites
Handy Don 17,359 #5 Posted 12 hours ago The HF tester can be helpful. It is in series with the plug, so it is simplistically testing both the ignition system and the plug at the same time--if either fails then no flash. That said, a solid spark will yield a very bright flash in the tester--a weak flash means a weak spark. If the HF tester is showing properly timed sparks, even weak ones, then the sensor module is not your issue. (The B&S tester, in contrast, can show a working ignition trying to spark a bad plug.) I’m assuming you’ve tested both spark plug leads. Given new, properly gapped plugs, a weak flash (vs. no flash) would have me checking for good spark plug wires as well as clean and solid electrical connections throughout the ignition circuit. Share this post Link to post Share on other sites
lynnmor 9,021 #6 Posted 9 hours ago Did you buy a Chinese ignition module? Perhaps you got a bad one. The fact that you get a spark when playing with switches and wires leads me to believe the module isn't switching cleanly. Share this post Link to post Share on other sites
ineedanother 2,830 #7 Posted 9 hours ago If you have a jumper with a clamp large enough to grip the plug, jumper it directly to the (-) on the battery. Eliminate a bad engine ground and see what your spark looks like. Share this post Link to post Share on other sites
TC10284 121 #8 Posted 6 hours ago I finally got it figured it after a bit of diagnosing. I think it turned out to be simply bad plug wires. Sigh... 2 Share this post Link to post Share on other sites
