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Ignition fuse keeps blowing???

Discussion in '40- & 55-Series Tech' started by cruzer, Mar 30, 2003.

  1. cruzer

    cruzer

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    Ok guys

    I am fighting my truck toothe and nail on this one. A few weeks ago i was driving my truck home and i noticed it wasn't charging so i checked stuff out and changed to a new alternator (all of 38 bucks for a LC 45amp Alternator at my local shop) So i put in the new alternator still nothing...ok so it must be the voltage regulator right? get a NEW electronic VR from parts place and put that in...STILL NOTHING>..WTF so then i notice the ignition fuse is blown..ok so much for looking at the simple stuff first...change the fuse everything looks great...THEN they keep blowing..so i am like WTF^2 so i go though and do all the checks on everything i can..everything checks out i am just not chargeing...i don't get it...So final i have my dad come look at it with me and we figure out the new VR is JUNK so i put the old mechanical one back in and it works...YIPPY...until this morning when i get in it to drive it and i am drawing 2amps again instead of Charging...WTF^3!! so i check the fuse and yup it's blown.....so now WTF^4 am i supposed to do....BUT the truck still runs and starts and drives with the ignition fuse blown...which i don't get....any thoughts? any suggestions? HHHHHHHHHEEEELLLLLLLPPPPPPPP i really need to drive this thing.


    STEW caught in an over current world
     
  2. thorvald

    thorvald .......

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    are you running stock wiring harness or aftermarket?
    i was blowing maxi fuse with painless so was pretty sure i didnt have a ground issue, pretty sure it was my voltage regulator. have you checked for bare wires?
     
  3. cruzer

    cruzer

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    Stock wiring harness....i went out there this afternoon and we put a shunt across the fuse to see how much voltage were were getting then did the V=I/R and figured out that when it blows it was like 34 ampsl...then we unplugged the Voltage regulator and plugged it back in and it seemed to work ok...then we beat on the voltage regulator with a pair of pliers and nothing...then i drove it around and nothing...but it looks like the VR is bad anyway...intermittently...Going to post that i am looking for a STOCK VR for a 75...see what comes up:)

    Stew
     
  4. Chef

    Chef

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    You can still get vr's from toyota, and there are a bunch of good used parts vendors, cruiserparts.net is nice, tell james I sent you. If replacing the vr next time around doesn't do it you're gonna have to get out a schematic and run the charging circuit, fuses don't go for no reason, and not fixing now could lead to a bigger problem in the future...Org say "fire bad..." Did you check the fusible links at the battery and the ammeter?
     
  5. CruisinGA

    CruisinGA

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    I don't think your voltage reg is bad. I replaced my original on my '74 with direct replacement one from Napa, and it works fine. Its something else. Sorry I can't be anymore specific than that, you are going to have to do some heavy duty diagnosing. &nbsp:Does your amp meter spike or jump around a lot? Are you sure the new alternator isn't a later model internally regulated one? Sorry for the obvious, just trying to make sure we cover all the basics.
     
  6. thorvald

    thorvald .......

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    i believe theres a way to adjust the voltage regulator, dont know the particulars, but pretty sure ive heard that.
    i got a replacement one at napa cost $23 still have my old one just in case. have heard the new ones can go bad quickly
     
  7. cruzer

    cruzer

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    Yeah i realize that there could be bigger problems later like fire. If the fusable link was blown from the battery or ammeter to anywere then the thing would see no voltage. You can adjust the VR because it is a mechanical one (take the screws off and the cover comes off) The new "direct" replacement once are electronic and much more current sensitive. We used to blow them on our race car at school running a CBR600 motor all the time.

    Stewart
     
  8. Junk

    Junk

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    Don't know if this helps or not, but when I replaced my stock alt with meansuckgreen the alt was so powerfull that I kept blowing the 7.5 IGN fuse in my 80. I installed an auto reset circuit breaker in there and then it was fine. Note that this only happened when the second battery was drained.
     
  9. Erics75

    Erics75

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    By any chance do you have anything hooked up in parallel to your ignition like lights, gauges etc? If you do, that very possibly could be your problem.
     
  10. cruzer

    cruzer

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    Good input Junk and Erics75

    I have nothing hooked up in parrel with the ignition that i did. the PO wired all kinds of crap into this thing but i ripped it all out. It seems that the VR is bad as i am not really charging much at all. The fuse hasn't blown yet in 3 days which is good.

    Stewart