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Discussion Starter · #1 ·
Last weekend after replacing my port side engines water pump, coming back from the test run, my starboard motor decided it wasn't done and continued to run even with the key out of the ignition. Installed a new key switch, didn't solve the problem. Had someone look at it and they said it was a bad alternator. I replaced the alternator last night. Will test it out today. I'm just curious if anyone else has had this problem. Could it be anything else, am I missing something, should I look anywhere else? All thought and feeling are welcomed.
 

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just a thought....

My boat has a big battery type ground cable that jumps between the 2 motors in the front. It gets bolted to the port side water pump/fuel pump housing. since you had that out, maybe you missed putting the ground back on ? I did this once and my strbrd motor did some goofy chit.
 

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I have been working on tach bounce issues. Before my last trip out I decided to tie together the 12v wires on the back of the tachs. This made it so my port engine would not shut off when my sb engines key was still on. So, what you have is somehow 12v is getting to the positive side of your coil continually. I would guess you have a short in the wire harness that runs right above your water pump. I'm thinking the purple wire (runs to your alt) has been pinched together with a 12v source. Start the engine, turn off the key and start giggling these wires to see if the engine shuts off.
 

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:iagree: once the alternator regulator is triggered it will keep the engine running.
 

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Discussion Starter · #5 ·
I haven't played around with any wires. Only replaced the water pump on the opposite engine. The person who suggested replacing the alternator, said there must be a bad coil in the alt which is holding the 12v charge and allowing it to run. I'm having my doubts though. The prior week, I did have some battery issues. When they put my boat in the water two weeks ago, they said the starboard battery had a very low charge. Both batteries are brand new this year, so they should be low, I believed it was from them leaving the battery switches on, but linked to the alt problem, I think the two might be related. I guess I'll find out tonight.

If I cut the battery switch will that shut the engine off, I don't know how they cut it when it first happened?
 

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AFter engine is running, the alternator takes over. You can actually remove batteries while engines are running and they will stay running.

2nd, if Alternator is bad, engine will die when positive cabel is removed while running. if this happens, JUNK ALTERNATOR.
please rev engine before dooing above #2 statement, do this to energize alternator, at least 1,300 RPM for older alternators. then remove Positive cable to check condition of alternator at an Idle.
Solo
 
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