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77 gmc jimmy starter/ volts problem, please help want to go wheeling!!

Discussion in 'The Garage' started by chevyguybc, Jul 25, 2006.

  1. chevyguybc

    chevyguybc 1/2 ton status

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    okay 77 gmc jimmy, with factory 305, but has cam, intake carb headers, etc

    okay to the starter i have the 1 11/32 nut wire, then the two 9/16 nut wires,( battery, and harness
    )

    are there any other wires that go to the starter because i have 4 cut wires ending right around the starter... they are cut not melted

    1 is blue
    1 is green
    1 is tan
    1 is light brown...

    any idea on what they do

    also when my key is in the on position.. my distribitor bat wire( orange).. gets 12 volts,, but when i crank the whole circuit goes to 7 volts

    is my regular garbage or what else could it be, i hate eletrical..
     
  2. goldwing2000

    goldwing2000 Guest

    The cut wires are probably your fusible links and original charging circuit.

    When the vehicle was new, the starter B+ terminal was used as the main junction block but most people eventually bypassed it because it was such a PITA to work on.
    You'll need to trace back all of those cut wires and see if they are attached to anything at the other end. If they are, you'll need to get power to them some way.
    What are the three wires on the alternator hooked up to? The main lug on the back should have a big wire with constant battery voltage. Same for one of the small wires. The other small wire should have key-on voltage of slightly less than the battery.
    Check this web page to make sure your alternator is wired up correctly.

    A voltage drop during cranking is normal but that much is excessive. What is the battery voltage during cranking? If your batt voltage is also dropping to 7V during cranking, then either your battery or your starter is toast. Unless your battery is WAY under-sized, it should only drop to around 10V.
     
  3. chevyguybc

    chevyguybc 1/2 ton status

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    well, i had a friend come over and he found that i was missing the ground on the back of the cylinder head. so now it cranks no problem and has major spark, i think that was it.. i just need plugs now because they are fouled,lol:D

    thanks for your help by the way, im going to bcome a member asap
     
  4. goldwing2000

    goldwing2000 Guest

    If that was the problem, then you better make sure that your grounds are set up properly.

    The ground cable from the battery should be going to the engine block or intake manifold. In addition to the head strap, there should be a ground wire between the radiator support and the frame rail on the right side.

    The strap at the back of the head won't stand up to cranking amperage for very long.
     
  5. chevyguybc

    chevyguybc 1/2 ton status

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    just tossed plugs into it, and major spark last night.. need a lower rad hose and im cranking again, hopefully its on top dead center, i didnt bother pullin a valve cover cause the rotor was 180 out when i got it to tdc, its all a big game until it fires
     

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