Alternator troubles.
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Alternator troubles.

  1. #1
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    Default Alternator troubles.

    Hey guys I've got a 91 Carrera elite 205, 454 hardin marine engine and the alternator is giving me troubles. boat will start up and run but won't shut off until I remove the IGN wire that goes from the alt to my terminal block setup. So I'm looking for a replacement. My current alternator is a prestolite 37A not sure if its a 1 wire or 2, (not familiar with alternators). Got some pics of the one I pulled out here, any help would be great in what direction I should go. Also its only a 10Awg wire that feeds it fyi.

    Adam
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  3. #2
    Senior Member 67weiman's Avatar
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    Is this a New to you boat or did this just start happening?

  4. #3
    Senior Member uniboarder's Avatar
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    If it won't turn off I doubt its the alternater. Check the ignition switch.

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    Senior Member Mojave85's Avatar
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    I am willing to bet it is the alternator not working. Since you already have it taken out take it down to your local parts store and have them check it out for you.

  7. #5
    Senior Member 67weiman's Avatar
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    Sounds like it needs a diode on the IGN wire. This is common in some aftermarket alternator and/or shotty wiring. I don't recall the correct diode but if you do a search you will get your answer on the correct diode

  8. #6
    Senior Member jetboatperformance's Avatar
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    Assuming its the OEM Alternator (and It appears to be) and... there are or have been no other changes made in wiring and it worked properly prior *, then the Alternator is likely failed internally and could be feeding back (as suggested above ) thru into the ignition via the alternator internal "excite" circuit . Do not buy an auto type unit from a parts store, they are not marine approved and they too could feed back , would recommend you replace the Prestolite deal with a Delco Marine approved "one wire" self exciting alternator particularly anytime you have a covered or partially covered engine environment Tom


    * if this situation is new following some recent work then the diagnosis decision tree could take a different turn ...

    * Re an in line wire diode (one way "valve" for current) if necessary.. its used in line to apply switchable 12v ignition current to the alternator excite circuit and the diode disallows current to allow feedback , easily tested with a test lite or multimeter

  9. #7
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    The stock alternator caused these problems about 2 years go, (ive had the boat 3 years prior to it giving me problems). checked the ignition switch and i was getting a backfeed from the stock alt. I replaced the alternator with an auto one, no back feed on ign, and that worked until end of last summer. pulled that had it tested and it failed. So im definitely going to go with a marine this time (do it right) but since the stock one I have can't be crossed referenced with the part number do I just try and find one that looks similar to the bolt setup of the stock? I don't really have any marine places that I know of near me to compare side by side. I live in Orange county CA.

  10. #8
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    im in huntington beach and i have a motorola single wire alternator that is a direct fit that you can have to test to see if its your alternator. it was removed from my jet boat in working order. its lower amp, but should be plenty to run a boat for testing.

    just a FYI there is a "high performance swapmeet" in long beach every month where you can pick up an alternator for a great deal. theres a guy there that rebuilds and refinishes them to new condition. i picked up this 165 amp unit for under $100. krinkle finish, 3 wire so it excites at low rpms, easy to wire up. bottom left in the pic...



    Long Beach | High Performance Swap Meet

    let me know if you're interested. the next swap meet is this sunday. ill prolly roll there just to look around.
    Last edited by ka0tyk; 03-31-2014 at 10:53 PM.

  11. #9
    "I'm just SPRAYIN' man!!" '78 Crusader's Avatar
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    Quote Originally Posted by brtn8187 View Post
    The stock alternator caused these problems about 2 years go, (ive had the boat 3 years prior to it giving me problems). checked the ignition switch and i was getting a backfeed from the stock alt. I replaced the alternator with an auto one, no back feed on ign, and that worked until end of last summer. pulled that had it tested and it failed. So im definitely going to go with a marine this time (do it right) but since the stock one I have can't be crossed referenced with the part number do I just try and find one that looks similar to the bolt setup of the stock? I don't really have any marine places that I know of near me to compare side by side. I live in Orange county CA.
    Call DB Electrical, they have marine Alternators.

    DB Electrical

    A Marine Alternator isn't necessarily any better than an automotive one....it just has extra shielding to keep sparks from exiting the alternator itself...it's safer to use in an enclosed engine compartment. So I seriously doubt you'll get anymore longevity out of a marine alt than the autozone one you're replacing.

    Like was mentioned earlier, I personally think you have an ignition switch issue.

    Good luck and please post up what you've found.
    Last edited by '78 Crusader; 04-01-2014 at 08:10 AM.
    Cliff
    1978 21' Crusader, 466 CID BBF, Berkely Jet
    1966 13' Boston Whaler sport, 40 HP Yamaha Two Smoker

  12. #10
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    Hey ka0tyk, as far as testing goes I store the boat in needles and I'm not sure when ill be back up there, are you interested in selling that one at all? and where is this swap meet at I definitely would like to check it out.... As far as the ignition switch goes I don't see how that could be the problem because it was working properly when I had a auto delco alt installed. I can however see that the excite of the alt has gone bad and is sending a back feed like jetboatperformance said.

  13. #11
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    Quote Originally Posted by brtn8187 View Post
    Hey ka0tyk, as far as testing goes I store the boat in needles and I'm not sure when ill be back up there, are you interested in selling that one at all? and where is this swap meet at I definitely would like to check it out.... As far as the ignition switch goes I don't see how that could be the problem because it was working properly when I had a auto delco alt installed. I can however see that the excite of the alt has gone bad and is sending a back feed like jetboatperformance said.
    you can have my old motorola. i dont need it. the long beach swapmeet is off of clark and carson at veterans memorial stadium parking lot. its huge and hard to miss. it costs $8 to get in and its put on by ecology. the link is in my post above as well.

    Long Beach | High Performance Swap Meet

    it starts at 6am and usually goes until 11am. the site says 1pm but people pack it up before that.

  14. #12
    Senior Member H20MOFO's Avatar
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    Quote Originally Posted by 67weiman View Post
    Sounds like it needs a diode on the IGN wire. This is common in some aftermarket alternator and/or shotty wiring. I don't recall the correct diode but if you do a search you will get your answer on the correct diode
    This and Toms post nailed it....for sure the diode.
    I played this game 25 years ago when I wired a v-drive from scratch.
    Another Hot Boat refugee

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