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Ignition Switch failing

Krsowles

Krsowles

New member
Hi all, I have a 1998 SeaRay 180 with the 3.0 Mercruiser. My issue is, last 2 times I’ve been out, the boat runs great but after 15-20 at modest speed (around 25 mph) the key switch burns out the ignition post. Boat dies and won’t crank. If I jump the solenoid to the starter it will crank but no spark. Curious what thoughts people have on this. Electrical workings are NOT my strong point and hoping someone who understands sorcery and black magic can clarify it for me! Thanks in advance.
 
Assuming nobody had added a bunch of accessories to the ignition circuit, I'd suspect a cheap switch was used. What brand was the replacement switch? Are the terminals on the ends of the wires properly crimped and clean?
 
Interesting thought. The only accessory added to the boat is a fish finder. I’m not sure if the radio is factory but it had one from the factory. Mechanic replaced switch after first time it died. The switch that came on boat when I bought did not have Sea Ray marked keys, either. Maybe 2 cheap key switches? Is there something in that circuit that could get hot enough to burn a cheap switch? Been going over connections this morning and have not found anything loose or corroded. I’m not too surprised because mechanic said they had gone over it all as well.
 
So doing things backwards today, I went over all connections and made sure they were good. Then I tried jumping the back of the switch B to I and B to S and still nothing. Here’s where I beat myself up and you’re welcome to join in; THEN I checked the fuses and the ignition one was burnt. So it starts now (again) but still afraid for whatever reason, the wire(s) are getting too hot and I need to resolve this. Still hoping for some great suggestions and I’m willing to take some abuse over NOT checking fuses first.
 
I’ll deepen the plot a little more; the first time the switch burned, we had been trolling all afternoon with no issues. At the end of fishing, we decided to spin around the small lake pretty much wide open just for fun. It lasted about 15 minutes until it died. Yesterday, same story. We basically idled around for quite a while and almost out lines out but I wanted to see what happened if we went faster. Again, 15-20 minutes of large ovals so I could still see boat launch (just in case) the ignition fuse popped. I’m starting to think perhaps the tach is bleeding energy back to system and the high speeds burn things up while idling doesn’t because the rpm’s are so low. Any suggestions on how to check this for dummies would be greatly appreciated. Mechanics are all a couple weeks out here (good for them!) and I’d like to fish. Thanks again!
 
More likely a bad ignition coil rather than the "tach is bleeding energy back..." Over torquing the screws on the back of a cheap ignition may damage it mechanically and lead to a poor connection internally which will generate heat. Unless you have a "ACC" position on the ignition switch and use that to power the fishfiner( and your other electronics, ( instead of connecting the electronics to the "ON" terminal of an "OFF"--- "ON (IGN)"--- "START" switch) you are misusing the intended use of the "ON(IGN) terminal" .
 
Thank you, I will look into that, coils are pretty reasonable and it can be ruled out that way. The fish finder is wired into the fuse block directly and has its own fuse. I used the accessory slot that was empty. I hope that’s what you mean. I do know it stays on if I don’t turn it off. I’d rather have it go off with key.
 
The normal (OEM) dash harness will supply over 40 amps via the B+ lead at the ignition switch...

Things normally burn/char/heatup where there is excessive resistance....

I'd suggest measuring the current being drawn thru the dash harness with different engine RPM...an IR temp gun is another approach...
 
That’s a great idea, thanks! I’m assuming you mean wires to ignition switch when you say dash harness? I’ll at least start there. Someone said the tach itself may be bad and could cause me headaches. Does that sound possible?
 
yes, specifically, the RED and BLACK wires, as a pair.

Normally, when the tach fails in a manner to inhibit the ignition, it doesn't contribute to burnt connections...but that would depend on the failure mode. You can disconnect the tach and see if the problem subsides.

You can also check for any issues with the PUR (IGN) lead back on the engine side of the main harness connector. Its possible the insulation is damaged and you are getting a true short to ground that is contributing to the issue.
 
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