[AndyFL]

My 2006 Mercruiser 4.3L TKS 190HP I/O ran fine for about 45 minutes before dying/stalling out while underway and without warning at about 1800 RPM. I tried to start up the engine but it was completely dead; no engine cranking sound, no audio warning alarm either. I checked all electrical gauges and all were out. I then checked all battery connections, fuses, wiring, etc and all seemed normal. I resetted the 50 Amp "Reset" button for the electrical overload protection system and finally the engine started up. I turned around back to port and engine ran fine for 10-15 mins, but it stalled again at about the same RPM and conditions as before. After resetting the overload electrical system breaker for a second time, the engine finally restarted and I was able to get safe to port but only at a very low RPM and almost idling speed.

I tested the battery and is OK, checked all wires, wiring harness, etc., all everything looks normal.

Anyone had experienced this problem? Any idea what might be causing this?

Thanks, Andy

[ShabahZ250]

Hmm, if it's tripping your main circuit breaker, I'd say you've got a serious electrical problem with the engine. This might require professional service.

I'm wondering if it could be your alternator possibly overloading the system?

[dieselwiezil]

Im not a "boat mechanic" but you got a major short to ground. If you suspect your alternator, detach the larger wire that comes from the starter or 12v source. That will cut the supply to the alt. Another thing I have run into is look CAREFULLY around your engine and make sure there are no wires rubbing anything on the engine or any type of bare metal grounded to the boat. Iwould bet thats your problem over the alternator.

[AndyFL]

Thanks for your replies guys.

As I was already aware, troubleshooting an electrical problem is not an easy task. I am at a dead-end here; I had been told to check all wiring, connections, harness, ignition coil, alternator, belt tension, trim pump, starter, circuit braker, etc., but I can't seem to locate and pin point my engine's culprit. I am hopeless and will have to let a Merc mechanic diagnose and repair my engine. I am sure he will find what's wrong fairly quick.

I'll keep you posted as to what turns out and what's the final tab.

[ShabahZ250]

In a situation like this, I would recommend taking it to a service facility. 50amps is quite a jolt if you came in the middle of the circuit path. Better safe than sorry. Let us know how it turns out!

[dieselwiezil]

I have a feeling it will be a quite simple fix. I think your problem is from your batt to starter to alternator. All those wires are a pretty good gauge wire. Any bare spots in those wires would cause this problem. Do you have ANY mechanical background? If not, than I agree the best thing to do is take to a professional. If you would like some troubleshooting help shoot me a PM.

[dudders]

Originally Posted by ShabahZ250

In a situation like this, I would recommend taking it to a service facility. 50amps is quite a jolt if you came in the middle of the circuit path. Better safe than sorry. Let us know how it turns out!

See what happens when you play with electricity and yourself at the same time?

[AirNavy]

I'm not sure if this one has been fixed yet, but if all of the insulation on the wires looks good and there's no visible corrosion at the terminals I would replace the circuit breaker. The contacts in the breaker can corrode causing a high resistance which will trip them well below their rated current because of the heat genertaed by the extra resistance.

[AndyFL]

Mickey:

The problem has indeed been resolved and your suggestion hit the nail right on the head.

I ended up replacing the breaker, ($60.00 part), and problem solved. When I removed the old one, it wasn't corroded at all, but found that one of the two male connectors was loose and had a lot of play, and with engine vibration, that kept tripping the breaker.

Thanks, Andy