Hi everyone, I've been working on small engines for years but never been as frustrated as I am now trying to get spark. A neighbor brought his atv over because he couldn't get it started after several years of sitting. After doing some basic checking I found the stator was bad.after the stator replacement it fired right up and ran great. Problem solved! Wrong. About six weeks later he brought it back and it had done the same thing. It sat for about a week and then he couldn't get started. Again there was no spark. I have eliminated kill switch neutral safety switch ignition etc. There is no voltage getting to the coil. However it does flash some power as soon as I let off the crank/start button, sometimes up to 120v ac. The pulse generator sends no power to the CDI box except flashes when you let off the start/crank button. I replaced the pulse generator when I replace the stator. It currently test 380 ohms resistance. Ive replaced the CDI, alarm box coil and done every continuity check I can find in the wiring diagram for the harness. Just no power unless the start button is released. I really don't want to just throw more parts at it, just don't know what else to do. Any help would be appreciated

 

Have you check diode at front ?

 

This problem is common on ATVs, lots of posts on here about it, no answers, some recon it is the pulse generator, so you may have got a dud. I sometimes wonder if the unit has been knocked and moved slightly too far from the flywheel, no definitive answers though. One point I do know is you get a better spark in neutral due to that wire from neutral light circuit being wired into the CDI. If that isn't getting the signal, you do get a poor, invisible spark when tuning the engine on the starter, but it must be good enough when running, or it would stop when you engage a gear.

All I can say is many of the 300s and 350s I maintain have the fault, owners learn to press the start button on and off in short bursts, as the start or end of one burst will "catch" and the engine start to run.

Just a thought, but I think there are five different CDIs for 300s, depending on year. First three all look identical, but the neutral light signal is different. Wiring plug colours differ but aftermarket CDIs all have off-white plugs. Did you buy the right CDI for an 88 300?

 

My coil reads 1.7 ohms. I am going to cook the CDI box. 192.168.100.1 192.168.1.1