cummins engine breaker tripping

[RussL]

Hi everyone, I’m in a bit of a bind and could use some help. I have a 2000 Carver 396 with twin cummins 6BT 5.9 engines. Last week I was motoring to have my boat lifted at another marina and the starboard engine quite running. A little searching reviewed that the 10 amp breaker on top of the engine had tripped shutting off the fuel. It continues to trip when you turn on the key. I can’t get a mechanic because they are booked up for most of the summer. Disconnected the fuel shutoff and tied it open and I was able to get the engine started and stayed running , but it tripped again right away. To make things worse the transmission won’t shift without the power. Any help would be appreciated.



Thanks,
Russ

[Viper]

I've seen those breakers fail a few times. Swap it out with the other engine and see if the fault follows the same breaker to the other side. If it does, replace the breaker. If it doesn't, you have some further diagnosing to do. Check all your connection to ensure they are clean, tight, and that there are no wiring shorts. That includes harness plug pins. If everything checks out at the engine, check the wring and connections behind the dash panel. If the wiring checks out okay, you'll have to check individual electrical components on that circuit which could be anything in the dash and on the engine. Hopefully no accessories have been added on to that circuit causing an overload condition that the circuit was not designed for. People tend to get lazy and pick the easiest/closest spot to get power when installing an accessory.

[km1125]

Agree with Viper... easiest, quickest and cheapest to just swap with the other side to see if it's just a bad breaker. If someone has a clamp-on DC ammeter, you could also check with that.

[RussL]

Thank you both. I am headed back up to the boat tomorrow. I will start by swapping the switch and checking/cleaning connections. I will report back once I am done with that. Do you know if that breaker is associated with the pre-heater? It was serviced recently. We have only run the boat a few hours since then. Just trying to draw lines at this point.

[km1125]

I'd say "yes". That breaker feeds the line up to the helm, and it looks like the heater feed also comes from there.

Cummins_6BTA_wiring.jpg

[RussL]

Found my problem! It appear that after my pre-heaters were serviced the main wiring harness for the engine slid over to make contact with the exhaust manifold. It had melted the wire loom and coating on the positive wire. It was kinda hidden so we missed it at first. Who knew the stupid pre-heat alarm could sound so good! . Thanks for the help!!!

[bud37]

Good catch....so many times things happen after some sort of service or work going on around the engines....a foot in the wrong place etc.

[Viper]

Glad you found the problem and thanks for posting your findings

[mjk1040]

Make sure you inform the ones that did the service of your issue, so maybe they will be more careful on the next service job!

[RussL]

Thanks, I did. In fact we were about to need to be towed in. It would have been $2-3k. I would have been asking him for. I said it in a nice way