Johnson 90HP V4 Crossflow No Spark Issue

Hello, all! Long time lurker, first time poster. Search has always been my friend until now. I have a 1996 Johnson V4 90HP crossflow outboard (J90TLEDA) that I bought a year ago (on a pontoon). No issues with motor up to about 1 month ago.

A month ago, after spending 1-2 hours trolling, I shut off motor when we got in a school of fish to cast. Upon trying to restart, all I got was cranking, no fire at all. Turned on trolling motor and headed for ramp. Sometime along the way I tried to start again and it fired right up and I got pontoon back to ramp and off the water.

We took the boat out nearly every other day or more after that with no issues until about a week ago. Nearly same scenario, shut boat off and would not restart. Started trolling for home, every 10 minutes or so I would try to start the engine but it would only crank, no fire at all. Fellow fisherman heard repeated attempts to start and towed me in. Since then I've been trying to troubleshoot and replicate issue on muffs. Some days it runs like a champ, some days it won't fire at all.

When it is not running, I've hooked up a spark tester to each of the four cylinders and not seen a spark on any. I've disconnected the black/yellow stripe wire at power pack and still no spark. Wiggled harnesses hoping to find a short but nothing. Then go out the next day and it fires up immediately. Then perform same routine, wiggle wires and harnesses trying to get the motor to shut down but it runs great.

I have since replaced the rectifier/regulator as I did not have a tach reading, hoping that would also resolve the intermittent no spark problem. Now I have a solid tach reading when the motor is running, but motor will still run on random days, then not spark on others. Took a shot in the dark and replaced the power pack, but did not resolve the problem. Tonight motor ran great, put on water, ran for two hours with multiple engine stops and starts, but when I pushed away from shore to load on trailer it wouldn't start again. So I'm at my wits end, hence the post.

I have ordered but not yet received a DVA so that I can further test stator and timer base (both visually looked OK after pulling flywheel to change rectifier and resistance checks are OK). One other item I have read about is the flywheel can have damaged magnets that could cause the problem (this seems rare). I'm really leaning toward electrical because of the either runs great or doesn't fire at all situation. Does unplugging the black/yellow stripe wire rule out ignition switch issues? After a day or two of repeated no starts with that black/yellow stripe wire disconnected, it did fire up and run great. Could not turn off motor with key though as the black/yellow wire was disconnected, or so I think (I opened primer valve to flood motor to shut off).

A couple of things I have noticed... Motor has never quit while running, it just doesn't restart. Battery swapped with known good without change, cranks very fast. Rectifier and power pack swapped out without resolving the issue. Leaning toward a bum wire somewhere grounding out but no luck using my very scientific wire wiggle method of isolation. I'm hoping to get a few more ideas I can try before I haul the old girl to the service center. Where, no doubt, it will run without issue.

I'm all ears if anyone has an idea for me to try while waiting for DVA to arrive. Hoping to find someone that has chased down a similar issue. The intermittent electrical issues to me are the worst!

Thanks for reading and for any help you can provide!

-Jerry

More knowledgeable fellows will probably be along, but while you are waiting...I know you said you tried a different battery, but I would sure double check all of the starting system. Pretty sure these motors have to turn above 300 rpm to generate any spark. So I would load test battery, replace solenoid ( they are not expensive), and open up the starter to clean it and change the brushes. None of that will cost a lot, and at worst it will eliminate one variable as you go forward.

Look real closely at the timer base and the stator. JMO

Thank you very much for giving me a few more things to check. I have a handheld tach somewhere around here that I can verify cranking RPM with, will post back results. Also got notified that the DVA peak meter has arrived so I might be able to do a few tests on the timer base and the stator before I throw more money at it, but those items are on list. I've got the factory service manual and the CDI troubleshooting PDF.

Is it wise to change the timer base and stator at the same time?

I also remember reading somewhere that you could isolate electrical issues to the boat or to the motor if you disconnect the "big red plug", then jump the solenoid. I think Johnson quit using that plug in 1995 (mine is a '96). Can I do something similar by disconnecting the harnesses that come from the helm? I know I have mess of wires under the helm and it would be helpful if I could rule that out until I can get in there and dress it up.

riopga said:

More knowledgeable fellows will probably be along, but while you are waiting...I know you said you tried a different battery, but I would sure double check all of the starting system. Pretty sure these motors have to turn above 300 rpm to generate any spark. So I would load test battery, replace solenoid ( they are not expensive), and open up the starter to clean it and change the brushes. None of that will cost a lot, and at worst it will eliminate one variable as you go forward.

Click to expand...

Just tested cranking RPM, all three times it was 370-380 RPM. It certainly won’t hurt to do the other items you recommend, so thanks for that info!

-jj

Boobie gets a gold star! Stator arrived in the mail Thursday, installed Friday, and we spent all weekend on the pontoon. Probably put at least 16 hours on it with no problems. A big thanks to all and I really appreciate this forum!