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Old 08-12-2013, 12:30 PM   #1
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Default 50 AMP circuit breaker popping

1994 SR 1800 4.3L LX Mercruiser
The circuit breaker mounted on the engine is popping during start-up. The first time (2 weeks ago) I reset it and everything worked fine. This week I had to hold the CB in while starting the engine. The question is this, is the CB bad or is this an indication of a more serious issue? I have lost my confidence in the boat and don't want to strand the family for a third time!
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Old 08-12-2013, 12:58 PM   #2
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are you starting on one battery or both? only one battery per the mercruiser manual.

sounds like a short, so pull all the fuses out under the dash, and disconnect all the extra wires to the batteries, and then try to start the boat.

keep, installing the fuses, and running the boat until you have the breaker pop again to pin point the circuit.
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Old 08-12-2013, 01:58 PM   #3
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I don't think it's a short.

My guesses would be that either the breaker itself has gone bad - it happens, or the starter is drawing more AMPs than it normally should and is thus tripping the breaker (if the latter then the breaker is doing exactly what it should be doing). I would start by first replacing the breaker and checking/cleaning all battery cable connections, and if that doesn't do it then pull the starter and have it tested or replaced.

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Old 08-12-2013, 03:33 PM   #4
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It only has the one battery.
I just replaced the starter earlier in the year with the proper starter, but will check the draw with a meter.
I also just realized that the nav and anchor lights stopped working as well. So it looks like I have a day chasing wires ahead of me!
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Old 08-12-2013, 04:34 PM   #5
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I agree with Dan here. Once running does the breaker trip? If not then not an issue with running power i.e. pulling helm fuses won't isolate issue. I don't recommend holding the breaker in because if there really is a fault it may result in melting the wiring.

BTY how are you planning to check the current draw of the starter? It pulls 100's of amps so a handheld meter will fry. Requires a meter rated for that much power.
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Old 08-12-2013, 05:03 PM   #6
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Mike- never looked into it so had no idea...

Once the engine is running, there doesn't seem to be any issues. If the starter was overdrawing, would it pop the CB every time I tried to start it? It seems to start at the house just fine when I Pre-trip test the boat.

edit- THANKS for the help!
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Old 08-12-2013, 10:21 PM   #7
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If it was the starter I would expect it to happen every time. But (and I am stretching here) if the starter is cool at your house it may draw less current but still hot when you launch the boat.

Best I can offer is to replace the breaker and let us know what happens.
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Old 08-19-2013, 07:08 PM   #8
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Your problem is described as intermittent - this most likely means a fault somewhere in the circuit. Best advice is to seek professional service. Don't take chances if you don't know what you are doing. Doing so can turn a minor problem into a major one. Furthermore, don't circumvent the job of the breaker by trying to prevent its operation. It's tripping for a reason. Again, seek professional service!
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Old 08-26-2013, 02:39 PM   #9
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I replaced the circuit breaker this weekend and the engine started normally. The real test will be when I can get it back in the water for the day. The CB that I removed did not feel near as smooth and the new one when the reset button is pushed. I'll let you know the end result after "sea trials"...
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Old 09-03-2013, 01:00 PM   #10
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Sea trial failed and had to be towed in. Started fine at the house and ramp, started several times while pulling the tube. Once a wet tube and bodies came aboard the engine would not start. Dead in the water for over an hour! Got the boat back to the house and it started the first time
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