Questions about My new boat
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Questions about My new boat

  1. #1
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    Default Questions about My new boat

    I bought a boat from a guy and he said the alternator was producing too many volts so when you go to shut the boat off it wont kill it. Key off and still running you have to pull the coil plug to kill it. He says that creating too many volts causes it to have an open circuit after its turned off and will just continue to run. Anyone ever heard of anything like that? Can you fix it or just buy a new alternator? Also it has a 750 holley marine carb on it that needs to be gone through, was just thinking about replacing it, Anything wrong with replacing it with a non-marine carb?

    Thanks for reading my questions hopefully I can get some help. Thanks!

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  3. #2
    Senior Member DuaneHTP's Avatar
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    Sounds like you need to put a diode in the exciter wire going to the alternator. I doubt it's too high of voltage. What does the volt meter say when running? Shoud be about 14.2 volts.

    Stay with the marine carburetor. That's what they are made for. If you use automotive carb and have a fire, your insurance may not pay.

  4. #3
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    Running at 16 volts if I remember correctly thats why I thought it was running high, I just bought the boat today havent done much remedying just wanted to run it across here to maybe get some ideas first. What would cause to run higher volts? And cool thanks for the advice on the carb.

    Quote Originally Posted by DuaneHTP View Post
    Sounds like you need to put a diode in the exciter wire going to the alternator. I doubt it's too high of voltage. What does the volt meter say when running? Shoud be about 14.2 volts.

    Stay with the marine carburetor. That's what they are made for. If you use automotive carb and have a fire, your insurance may not pay.

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  6. #4
    '74 Sanger ski hydro the General's Avatar
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    Never heard of that before, but my .02 an easy check would be to take the alternator belt off, start it and try to kill it.
    Not sure what kinda boat you bought but if the engine compartment is enclosed, I'd stick with marine specific components (carb, alt, fuel pump, etc.) and use your bilge blower

    1 more thing.... don't pull that coil wire off to kill the engine while in the water behind the boat
    87 Kustom Kraft open bow cruiser jet
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    74 Sanger ski hydro v-drive

  7. #5
    Senior Member Texgo's Avatar
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    Just take the hot wire off of the alternator.

  8. #6
    Senior Member jetboatperformance's Avatar
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    Chances are someone has installed an automotive application alternator on your rig , if your alternator has a large and small lead , the B+ (large wire) is OK with direct battery current but like Duane indicated the smaller wire needs to be "switchable" and will require a inline directional diode or even a small inline "idiot lite" to avoid signal feedback into the ignition system which likely shares that same circuit , the flow of current thru the diode needs to power up the excite circuit in the alternator but not back to the dash and back to the coil. . Again like said however with non marine parts eg Alternators, carbs ,starters etc one runs the risk of problems (fire,bilge explosions etc ) call if you need tech help

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    Awesome thanks for the information I really appreciate it!

    Quote Originally Posted by jetboatperformance View Post
    Chances are someone has installed an automotive application alternator on your rig , if your alternator has a large and small lead , the B+ (large wire) is OK with direct battery current but like Duane indicated the smaller wire needs to be "switchable" and will require a inline directional diode or even a small inline "idiot lite" to avoid signal feedback into the ignition system which likely shares that same circuit , the flow of current thru the diode needs to power up the excite circuit in the alternator but not back to the dash and back to the coil. . Again like said however with non marine parts eg Alternators, carbs ,starters etc one runs the risk of problems (fire,bilge explosions etc ) call if you need tech help

  10. #8
    Member 67CarlsonChryslerVdrive's Avatar
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    BTW if the alternator is truly running at 16 volts it will fry the battery in no time. If it is running that high then the regulator either internal or external is not working so make sure to replace that as well. I agree with what everyone here is saying about someone putting an automotive alternator in the boat. Had a buddy do the same thing and caused the same issue. I wired in a relay that activated with the key on to cause the shutdown properly.
    67 Carlson V-Drive retired Circle track race boat Originally equipped with a 426 Max wedge with a cross ram intake, getting a 440
    74 Chrysler Conqeror SIII Superbee Jet 340, Has a Chrysler jet pump and 340 long gone getting a 360 Magnum

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