3.0 popping breaker (I think) under load then not resetting / restarting.

[pmtom1]

1996 3.0 in 18' Sea Ray. Been having intermittent issues for last two weeks. Starts and idles fine. Runs fine going slow. While running at 3800-4000 there has been random, very quick RPM drops. Sometimes it just picks right up again, other times it stalls. Thought it was carb / fuel issue so was tracing that down but couple days ago, went to start it and nothing happened. SLIGHT click from rear. Checked circuit breaker (felt normal) so checked battery voltage (12.5). Checked with test light to both sides of relay, then to slave, then starter. All good. But no turn over with key. Jumped starter posts with screw driver and engine turned over fine. Then went back to start switch and she started up fine. Ran by myself quick blast for 15 minutes....perfect.

Yesterday get in with 3 people total and starts perfect, idles fine, leaves no wake zone fine. Then about 4 minutes in at about 3500 RPM, I get the drop again. THIS time I notice my GPS is off (Has to be manually turned on every time key goes off) so now I know its electrical, not carb / fuel. I throttle down and turn around it it dies.

Check breaker (feels fine) no start / nothing on gauges. Check battery with VM and its 12.5. Press breaker again, no dice. Then I jump starter again for a couple seconds (key was off). Go back to helm and it starts up. ride back to slip slow but no issues.

The ONLY thing different from last season is I had the constant (auto) power lead from bilge disconnected most of last year and I reconnected it this year before dropping in since it would be in water all the time.

Any ideas on where to start?

 

[Bt Doctur]

if the gauges dont come alive, your missing the 12v on the Red wire
if you shorting it at the starter, batteries and cables are ok
If shorting the two large lugs on the slave , the batteries and cables are ok
If slave is clicking but not turning the starter, you have a bad slave
If no clicking your missing the 12v from the "start" position of the key switch

 

[pmtom1]

Would bad slave cause issues while underway, under load? Or just while starting?

 

[Scott06]

Would bad slave cause issues while underway, under load? Or just while starting?

Just during starting, underway 12 v from switch to positive ignition coil keeps it running.

 

[TunaFish389]

I would check/clean grounds.

 

[pmtom1]

Ok...so think I figured it out. Last fall I pulled the engine and never mounted the circuit breaker back on the bracket because I was planning on replacing it. Today I noticed the mounting screws are grounds.

​​​​​​Didn't have the screws / bolts so wrapped a wire around the hole and connected to the bracket.

Ran perfect for 3 hours today. Wonder if that could have caused it.....

 

[GA_Boater]

Circuit breakers don't use grounds. Unless you're saying other things are grounded through the mounting screws.

But with a bouncing around circuit breaker, it could be popping because of mechanical trauma, not an electrical overload.