1992 Johnson 140 electric cut - protection circuit of some sort?

[jeffj254]

Hello everyone, I have a 1976 GlasPly 17' runabout with a 1992 Johnson 140 on it. This spring I've been having a strange electrical issue with it. Battery is fully charged, cables are tight, no corrosion that I can see. Sometimes when I use the trim/tilt, hit the starter, or even just turn the key on, I'll hear some kind of short high pitched noise from the motor, then all electrical power to the motor will be cut. Trim has no power, even the relays won't click. Starter won't engage, the warning horn in the controls won't chirp when you turn the key on. Gauges and lights on the dash seem normal though.

If you disconnect the battery, wait a second, then reconnect the battery, power will return and things work again. The issue is intermittent, sometimes everything works totally normal, no issues at all. Once the motor is running it does not cut out or show any signs of strange behavior. Runs, idles, accelerates just like it always has.

It seems like maybe there is some sort of protection circuit somewhere that is tripping and breaking the circuit but removing power resets this circuit. Is there anything like that in a 90s OMC outboard? Could it be something in the starter solenoid where the battery cable connects? Maybe some sort of flaky master fuse somewhere?

I've poked around the motor and tried to check for any bad or corroded connections but everything seems tight and clean.

I did have an issue with the trim relays recently where some sort of black insulating compound on the relay plugs had melted and was fouling up the contacts so the relays wouldn't fire. I cleaned them off and put some dielectric grease on and since then I haven't had any issues with the relays triggering. Doesn't seem like that would be related though.

I'm pretty stumped by what is going on. Any ideas?

 

[Bosunsmate]

May sound weird but id check your main wires are good, sometimes they corrode internally (you can often feel it when pressing the outer coating). And also check your battery connections on the inside are clean and also where the cables connect at the motor. Check the connection bolts are clean too and the ground threads into the motor.
I know youve checked them over but its a thorough internal look and clean that will be the thorough test.
Problems-dirt/corrosion on any of these parts can cause this

 

[w2much]

If you found bad connections on your relays there are others. Check all of your connections, wires, terminals et all. Look past your terminals for corroded wire inside the insulation. . Sometimes grease itself over time will harden up and become an insulator holding corrosive particles which will travel into your wiring. or at least block continuity.On my boat was a similar intermittant electrical issue with my trim and tilt. It usually worked, sometimes it did not. It worked less over time.I ran all of the test from the OMC factory repair manual on each seperate component of the trim and tilt system , Each on its own tested good. Last night I thought to give it another go. On my solonoid which I wire brushed on the outside and covered with liquid tape last year I think I have found the culprit. On the positive side of the solonoid there are four wires including the the positive wire from the battery. There are two nuts on the terminal with a washer sandwiching the wires together.. The connection looked good but thought it would be the best place to start to look for a weak or bad connection. One of the nuts was copper or brass as it should be. The other nut appeared to be the same. I took each one off. .The wires had tarnished and the grease I had put on for protection seamed to form a bit of an insulator. I wire brushed them all back to shiny copper color. The second nut seemed to be especially tarnished. I brushed it and brushed it some more. I then took some sand paper to it. The nut was steel . It had a protective coating of rust on it. For some reason, perhaps my aged eyesight it appeared to be copper colored. I believe I have found my problem. I cleaned all of this a year ago but the steel nut escaped my skill level. With electrical problems you need to go a bit deeper than the surface. Instead of thinking outside of the bun make sure the bun is 100% before moving on.

 

[jeffj254]

I think you may be on to something with the battery cables. I took the boat out today and was puttering around the lake, the horn in the controls started making some weird buzzing noises intermittently. Not the full on high pitched warning noises, just weird kinda buzzing noises that moved in tone with the engine RPM. Reminded me of a car stereo with a bad ground. I'm pretty sure there's no actual warning condition as the water coming out of the telltale seemed steady as ever and wasn't overly hot and it was pretty clearly getting oil from the smell of the exhaust. Oil tank is full too.

While this was going on I turned the motor off for a bit, when I went to start it again it started immediately but after a second it stopped and I lost all electrical power again. No chirp from the horn on key on, no starter, no trim. I went back and moved the battery cables around a bit without disconnecting them and power came back.

Seems like the battery cables could be a likely culprit here. I've also been noticing that the starter doesn't seem to crank as hard as it used to, even with a freshly charged, nearly new battery. It'll turn until the next cylinder compresses, then sorta pause for a second while it pushes past the compression, then it'll continue cranking. Seems like another sign that the cables might be corroded internally.

I think I can swap out the cables while the boat is in the water, the connection points aren't that tough to reach, so I think I'm going to try that. New cables aren't that expensive. Per my service manual I just need some 4AWG lines.

I'll report back after the swap

 

[boobie]

If you grind on the starter a little while feel of your battery cables and see if they're warm. Getting warm is a sure sign of corrosion internally.

 

[jeffj254]

That was a good idea! I went out today and hit the starter without hitting the enrichment and sure enough, the battery terminals got warm. Started looking more closely at the battery connections and cables and realized they were actually pretty corroded, especially underneath and on a secondary wire that was also connected on the post.

Went at the connections and terminals with some contact cleaner, brass brush, sandpaper and 3M metal scrub pad and got them back to shiny. Hooked everything back up and now the motor cranks hard without the weird delay, the trim tilt moves faster and sounds higher pitched and more energetic, and I'm not hearing any odd sounds from the warning horn when I cruise.

I did get a new set of battery cables, but I don't notice any "crunchiness" or stiffness in the current ones, and with the results from just a good cleaning of the connections I think I'll store the new cables for now and see how it runs with the old ones.

While I was at it I also found that the ground wire for the dash electrics was corroded and had some torn insulation on it, and the connector for the positive wire to the dash electrics broke when I tried to clean it.. That wouldn't affect the motor, but while I had the battery out I replaced the ground wire and cleaned up the connections on the rear ground block and put a new ring terminal on the positive dash wire so all the lighting, stereo, bilge, etc should continue to work.

One thing I noticed though is after polishing up the battery cable connections they're now copper colored instead of silver. I suspect they were originally tinned but the tin had corroded and has now been removed by my sanding/polishing. Should I coat the cables in something to keep the copper from going green? Is it possible to "re-tin" the connectors with some sort of dip? Or would some grease or something like that work?

I disconnect the battery on this boat pretty regularly so it'd be nice if it wasn't something I'd have to constantly re-apply.

Thanks for the suggestions all!

 

[Bosunsmate]

I put grease on mine, but that eventually goes bad, Im glad your problem is solved