1975 F250 starting problems

Discussion in 'Ford Truck Forum' started by chrokeva, Aug 25, 2012.

  1. chrokeva

    chrokeva Member

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    Have a 75 F250 w/360 tried to start it and it would turn over but die, rebuilt the carb with same results. everytime the starter is engaged the engine will fire, when the key is let go it dies. Im figuring electrical possibly the coil or maybe the ignition module, it has electronic ignition with the module. theres not much to the motor being a 75. I know if the items are broke replacement will be required, but how to tell which one.
     
  2. chevychase

    chevychase Semi-Admin
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    Sounds like the ignition .switch to me . See if there is power at ignition fuse when you let the key off.
     
  3. chrokeva

    chrokeva Member

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    would that be the switch itself on the dash or the module
     
  4. chevychase

    chevychase Semi-Admin
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    The switch on the dash turn it to on see if there is power on both side of the ignition fuse .
    Welcome to the site .
     
  5. chrokeva

    chrokeva Member

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    I havent had a chance to check the fuses but I know that if I turn the key on all the dash lights come on, does that mean there is power going through the switch?
     
  6. chevychase

    chevychase Semi-Admin
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    So your saying as long as starter is engaged turning the engine it runs? Try this check for power at the coil when key is on.
    Prime the engine see if it runs good for a few seconds when key is let off.
     
  7. chevychase

    chevychase Semi-Admin
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  8. elgemcdlf

    elgemcdlf Senior Member

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    Sounds like it might be a bad ballast resister. When cranking the resistor is bypassed providing 12V to the coil. When in run the resistor drops the voltage to something like 9.8V. I would run a wire from the + of the battery to the + of the coil & try to start. If it starts & stays running you are on the right track. To kill the engine you will need to disconnect this jumper wire. Do not run it this way as it will burn out your coil but you can do it for testing purposes.
     
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  9. chrokeva

    chrokeva Member

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    bought a new module and installed it, would not even fire even when starter engaged. put on the old one and when starter engaged fired until I released the key. bad module maybe, something else maybe. am going to use the jumper from the batt to the coil tomorrow, what size wire would be to small?
     
  10. chrokeva

    chrokeva Member

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    will run when starter engaged but dies when key is let go, if you prime it it just revs higher then dies.
     

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