Question on an alternator
+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 14 of 26

Thread:
Question on an alternator

  1. #1
    Half a bubble off jrork's Avatar
    Join Date
    Dec 2007
    Location
    Silverdale, Washington
    Posts
    2,467

    Default Question on an alternator

    Not my boat but my sons truck and it's got me stumped.

    85 Chev 1/2 ton with a small block. Ran perfect when he parked it.

    No start yesterday and we found the fuseable link was gone on the firewall. I had one of those marine style 30amp inlines so we threw that on there for grins and no problem. Truck fired right up.

    He got as far as the gas station and noticed the radio had quit working. Shut the motor off at the station and no start. It had blown the 30amp fuse.

    Plugged in another one and brought it home.

    With a fuse in it the radio is dependent on the rpms. Let off the gas and the radio works. Give it gas and it stops. Shut the truck off and it'll blow the 30amp fuse.

    I also noticed that when the radio quit the stock volt gauge would peg.

    I disconnected the alternator from the truck at the main post and found that everything works perfect. No blowing fuses, radio is perfect and all is well.

    On a whim I threw my digital voltmeter on the alternator main post (while it's still disconnected) with the truck running and found 34.3 volts coming off of it.

    I thought to myself "self, the regulator must be gone on this alternator" so I slapped on a used one I had in the shop and tada, same exact thing.

    Does anybody have any thoughts or ideas? I'm all ears.........thanks...john

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member GT Jets's Avatar
    Join Date
    Jun 2008
    Location
    Morgan Hill
    Posts
    2,234

    Default

    Sounds like something is amiss on the two wire plug on the side....This is the voltage signal that controls the alternator..If this voltage signal is low, the alternator will full field to try and build it back up...Check to make sure (engine off, key on) you have voltage going to the larger wire on the alternator lug (disconnected from the alt.), if not, hunt it down and repair it..Probably a corroded terminal in the main terminal block or something.

    Good luck!
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  4. #3
    Half a bubble off jrork's Avatar
    Join Date
    Dec 2007
    Location
    Silverdale, Washington
    Posts
    2,467

    Default

    Thanks Glenn.

    With the mail wire that attaches to the lug on the back of tha alternator disconnected, I have full battery voltage to that wire terminal. That is the wire that returns from where the fuseable link attached on the firewall.

    The #2 terminal on the side of the alternator comes up from the starter post. It has full battery voltage.

    The #1 terminal on the side of the alternator runs through the firewall and disappears into a maze of wires. With the key OFF, this appears to be grounded. With the key on, it shows battery voltage.

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    mo balls than $cents$ IMPATIENT 1's Avatar
    Join Date
    Dec 2007
    Location
    hugo,okla
    Posts
    11,733

    Default

    Quote Originally Posted by jrork View Post
    Thanks Glenn.

    With the mail wire that attaches to the lug on the back of tha alternator disconnected, I have full battery voltage to that wire terminal. That is the wire that returns from where the fuseable link attached on the firewall.

    The #2 terminal on the side of the alternator comes up from the starter post. It has full battery voltage.

    The #1 terminal on the side of the alternator runs through the firewall and disappears into a maze of wires. With the key OFF, this appears to be grounded. With the key on, it shows battery voltage.
    unhook #2 see what happens, sounds like the alt can't turn off to me, the wire #1 heading into the cab should be for the idiot lite or gauge, that's why you see voltage on it with the key on.
    a good starter and alternator shop can take your old 1 and convert it into a 1 wire alt, so then you'd just have the big heavy wire to the back and that's it, might be your best/quickest option, take the other alt back and get yo $$$$ back.
    Last edited by IMPATIENT 1; 01-18-2010 at 12:43 PM.

    Dare to be different, if it turns out great you can claim you planned it that way.

    Jetboatperformance.com

  7. #5
    Half a bubble off jrork's Avatar
    Join Date
    Dec 2007
    Location
    Silverdale, Washington
    Posts
    2,467

    Default

    Quote Originally Posted by IMPATIENT 1 View Post
    unhook #2 see what happens, sounds like the alt can't turn off to me, the wire #1 heading into the cab should be for the idiot lite or gauge, that's why you see voltage on it with the key on.
    a good starter and alternator shop can take your old 1 and convert it into a 1 wire alt, so then you'd just have the big heavy wire to the back and that's it, might be your best/quickest option, take the other alt back and get yo $$$$ back.
    Hmmmm, you might be on to sumthin. I plugged in a spare plug and jumpered out #1 completely eliminating #2 from the system. MONEY!!!!

    Between 14.1 and 14.2 volts on my voltmeter and in the truck.

    Now, what is the purpose of #2 if it works so well without it???

    Thanks so much guys. It's great to have some extra brains working on this with us......john

    ps... we didnt buy an alternator. These are just spares I have in the shop. Thanks again

  8. #6
    Senior Member GT Jets's Avatar
    Join Date
    Jun 2008
    Location
    Morgan Hill
    Posts
    2,234

    Default

    Quote Originally Posted by jrork View Post
    Thanks Glenn.

    With the mail wire that attaches to the lug on the back of tha alternator disconnected, I have full battery voltage to that wire terminal. That is the wire that returns from where the fuseable link attached on the firewall.

    The #2 terminal on the side of the alternator comes up from the starter post. It has full battery voltage.

    The #1 terminal on the side of the alternator runs through the firewall and disappears into a maze of wires. With the key OFF, this appears to be grounded. With the key on, it shows battery voltage.
    This is what you should see...Like IMPATIENT says, the little wire is the the Uhmm Uh HMMM IDIOT light LOL...

    You actually should see some resistance from it and not a direct "short to ground" but a reading over ground...

    Is it possible that the large wire from the solenoid is broken and intermittent? This is the wire the alternator gets the charge condition signal from, it also sounds like maybe you have a potential for a fire, keep a set of diagonals and a fire extinguisher close by (the diagonals are to cut the wire if needed. The alternator is capable of a lot more than 30 amps BTW, that should be at least a 50 amp deal...

    Also may want to check for a bad body ground...Or I guess an engine ground...It would be odd that two alternators do the same thing.

    When you read the disconnected alternator voltage, did you see AC or DC volts?
    Also, factory radio? Some stereo shops do weird stuff
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  9. #7
    Senior Member GT Jets's Avatar
    Join Date
    Jun 2008
    Location
    Morgan Hill
    Posts
    2,234

    Default

    Quote Originally Posted by jrork View Post
    Hmmmm, you might be on to sumthin. I plugged in a spare plug and jumpered out #1 completely eliminating #2 from the system. MONEY!!!!

    Between 14.1 and 14.2 volts on my voltmeter and in the truck.

    Now, what is the purpose of #2 if it works so well without it???

    Thanks so much guys. It's great to have some extra brains working on this with us......john

    ps... we didnt buy an alternator. These are just spares I have in the shop. Thanks again
    wire #2 is the "exciter" wire...Sounds like you may have put in a "Single wire" alt...
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  10. #8
    mo balls than $cents$ IMPATIENT 1's Avatar
    Join Date
    Dec 2007
    Location
    hugo,okla
    Posts
    11,733

    Default

    Quote Originally Posted by jrork View Post
    Hmmmm, you might be on to sumthin. I plugged in a spare plug and jumpered out #1 completely eliminating #2 from the system. MONEY!!!!

    Between 14.1 and 14.2 volts on my voltmeter and in the truck.

    Now, what is the purpose of #2 if it works so well without it???

    Thanks so much guys. It's great to have some extra brains working on this with us......john

    ps... we didnt buy an alternator. These are just spares I have in the shop. Thanks again
    let it run a bit and look again, i bet that 14.2 goes down quik, then again it may be charging, i've seen alot of dual hook up alt lately, the last 1 wire i bought for a boat could be hooked up either way and it'd charge.

    Dare to be different, if it turns out great you can claim you planned it that way.

    Jetboatperformance.com

  11. #9
    Half a bubble off jrork's Avatar
    Join Date
    Dec 2007
    Location
    Silverdale, Washington
    Posts
    2,467

    Default

    Wow this is wacky. It was working great with no drama and a steady 14.2 with #1 and #2 unplugged (making it work like a 1 wire). It ran that way for probably 15 minutes then took off on the charge voltage. I saw it and shut it down (and blew the fuse again).

    Plugged it in exactly like stock using the #1 and #2 wires and it's now been perfect.

    I traced the wires back to the solonoid and didnt see anything. I wiggled and pulled till I'm about crazy (there's a sig line for you) and it's working like it has for 3 years.

    Something is still amiss but it's gonna take some thinking for sure...

  12. #10
    mo balls than $cents$ IMPATIENT 1's Avatar
    Join Date
    Dec 2007
    Location
    hugo,okla
    Posts
    11,733

    Default

    voltage regulator is junkkkkk, take it to a alt shop and have it converted to 1 wire

    Dare to be different, if it turns out great you can claim you planned it that way.

    Jetboatperformance.com

  13. #11
    Senior Member GT Jets's Avatar
    Join Date
    Jun 2008
    Location
    Morgan Hill
    Posts
    2,234

    Default

    Quote Originally Posted by IMPATIENT 1 View Post
    let it run a bit and look again, i bet that 14.2 goes down quik, then again it may be charging, i've seen alot of dual hook up alt lately, the last 1 wire i bought for a boat could be hooked up either way and it'd charge.

    I believe the only difference on the "one wire regulator" is it is internally connected at terminal #2 and "out"...

    So both ways would make perfect sense...I just will not "reference" system voltage, but rather "battery voltage"..

    Does that sentence even work? LOL
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  14. #12
    mo balls than $cents$ IMPATIENT 1's Avatar
    Join Date
    Dec 2007
    Location
    hugo,okla
    Posts
    11,733

    Default

    Quote Originally Posted by GT Jets View Post
    I believe the only difference on the "one wire regulator" is it is internally connected at terminal #2 and "out"...

    So both ways would make perfect sense...I just will not "reference" system voltage, but rather "battery voltage"..

    Does that sentence even work? LOL
    i understood it lol the alt i had that would go either way had a regulator in it that was made to do that, i think i saw that same regulator on ebay for sale the other day for about 20bucks, not bad.most alt shops around here charge about 35bucks labor and parts to just go in and install the 1 wire regulator, i think it was around 45 for the dual hook up type installed. either way the easiest thing to do is just have the alt converted to 1 wire, be done with the headache. if you do the ole jumper way, the alt will be on all the time with the key on, which will overcharge too, the regulator has to be able to turn off as well as on.

    Dare to be different, if it turns out great you can claim you planned it that way.

    Jetboatperformance.com

  15. #13
    Senior Member GT Jets's Avatar
    Join Date
    Jun 2008
    Location
    Morgan Hill
    Posts
    2,234

    Default

    Quote Originally Posted by IMPATIENT 1 View Post
    i understood it lol the alt i had that would go either way had a regulator in it that was made to do that, i think i saw that same regulator on ebay for sale the other day for about 20bucks, not bad.most alt shops around here charge about 35bucks labor and parts to just go in and install the 1 wire regulator, i think it was around 45 for the dual hook up type installed. either way the easiest thing to do is just have the alt converted to 1 wire, be done with the headache. if you do the ole jumper way, the alt will be on all the time with the key on, which will overcharge too, the regulator has to be able to turn off as well as on.
    I don't think so...Not 100% certain, but the way GM wired their stuff was to but the battery voltage directly to the #2 plug connector...Up until computers that is...(different alternator all together)..

    Once the alternator stops spinning, the field collapses and it has to start all over again...you can literally run a short piece of wire from the post to #2 and be on your way, providing the regulator is not shorted that is...

    John, I think you will find you have a short somewhere, a big one...And it will be on a big red wire coming from the alternator, or somewhere close....Remember the fire extinguisher...I want to see Ian get some EFI stuff for the Sanger...
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  16. #14
    mo balls than $cents$ IMPATIENT 1's Avatar
    Join Date
    Dec 2007
    Location
    hugo,okla
    Posts
    11,733

    Default

    may be right, but he's still gotta bad regulator and it needs to be changed, better off just goin 1 wire now

    Dare to be different, if it turns out great you can claim you planned it that way.

    Jetboatperformance.com

+ Reply to Thread
Page 1 of 2 1 2 LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95