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7.3 Starting Problems

Discussion in 'Ford Trucks' started by redplowman, Feb 23, 2013.

  1. redplowman

    redplowman Member
    Messages: 61

    I will appreciate any help y'all might give with this problem!
    I have a 2001 Super Duty with a 7.3 diesel with 118,000 miles on it. I am having a problem with it starting cold. We have replace the glow plug relay, all the glow plugs, checked the glow plug harnesses as well as ohmed out all the glow plugs through the harnesses. We are 99.9% sure the glow plugs are working but still no cold start. If we plug the block heater in the truck will start in about 30 minutes. Other items we have checked is the high pressure oil pump and fuel filter. Does anyone have any other ideas of what it might be. Thanks for looking! :confused:
  2. White Gardens

    White Gardens 2000 Club Member
    Messages: 2,665

    Not plugging it in.

  3. redplowman

    redplowman Member
    Messages: 61

    I wouldn't think I would have to plug it in at 20 degrees.
  4. goel

    goel PlowSite.com Addict
    Messages: 1,079

    Cycle the glow plugs a few times. Does that make a difference?

    As long as mine is parked inside (unheated shop) it will start, And the block heater has not worked in a couple years.

    Now if its going to be colder than hill freezing over for a couple weeks straight I make sure it gets started regularly.
  5. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    Get volt multi tester and put on batteries do you see volts from 12.30 drop to 10.5-10.8 volts for like 5 seconds then creep up 11 volt stay for about 100 seconds if i remember.

    Until engine had low compression or injectors tired. Had you try 5w40 synth oil? I used to run those in tired injectors it help very much in cold outside.
  6. redplowman

    redplowman Member
    Messages: 61

    The oil is the recommended type and cycling does not help. Do you think the injectors could be bad at such a low millage?
  7. FordFisherman

    FordFisherman PlowSite.com Addict
    from 06611
    Messages: 1,613

    Have you checked that the HPOP reservoir is full? Just a thought.
  8. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    Too many to list.

    Not change oil on time, run on low fuel pressure, clogged fuel filter, and bad fuel can cause this.

    When I had tired injectors it wouldn't start or had very bad romp. Switch to 5w40 it like you had new engine ever start -5oF with no ROMP.

    Does it smoke when crank or none? If plug block heater for 20 mins does it smoke white?
  9. FordFisherman

    FordFisherman PlowSite.com Addict
    from 06611
    Messages: 1,613

    How does it run once its started? Try switching out the relay with a Fisher or Western relay. Had a Napa unit go bad on me in under a year. Just cause its new doesn't mean its good.
    Last edited: Feb 23, 2013
  10. dfd9

    dfd9 PlowSite.com Addict
    Messages: 1,475

    Since the last time I replied on a 7.3 cold start issue I got bit, check the oil. lol

    You shouldn't have to keep it plugged in, but it helps.


    Is your fuel draining back? Wasn't there an issue on diesels sometimes? Or something with the injectors, I'm too tired to remember.
  11. redplowman

    redplowman Member
    Messages: 61

    Oil was just changed, fuel filter does not look bad. It does blow out black smoke when it is cranking. The HPOP is full.
    Last edited: Feb 23, 2013
  12. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    I use Boss's relay I think trombetta it was best one I can find that handle glow plug system.
  13. diesel dave 04

    diesel dave 04 Senior Member
    Messages: 155

    Batteries are bad or the starter is drawing to many amps. (to slow of a crank speed with thick oil)
  14. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    Check batteries terminals. Make sure they are 100% CLEAN.
  15. redplowman

    redplowman Member
    Messages: 61

    2 new batteries, I'm not sure about the starter. cleaned all the battery and ground connections!
  16. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    Where you in Michigan?

    U need scanner to find what exact issue with this one.
  17. jmac5058

    jmac5058 Senior Member
    Messages: 431

    If the oil was no changed its whole life with the right oil the HPOP will make the injectors fail prematurely . Even having fresh oil will not improve this condition . I think its injectors from bad oil. There are fue diesel motors that use HPOP injection system but the 7.3 is one of them. Theres a guy on you tube that shows you how to change the HPOP oil on a 7.3 this can sometimes get your injectors to work better.I think his name is Powerstroke help from Georgia.
  18. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    ^ Here one word for you. Stop believe what he say. Every words come out his mouth is blah to get you fall in his gimmick words on youtube.
  19. TLK380

    TLK380 Member
    Messages: 65

    Check your fuel filter.
    I changed mine and after removing it i saw about 1/4 " of debris on the bottom of that can.
    If it gets dirty again real fast then check your fuel tank for delamination.
    Hope that helps.
  20. brad96z28

    brad96z28 PlowSite.com Addict
    Messages: 1,525

    On a few trucks I have fixed that had bad glow plug relay I could not get the computer to send a signal to the gp realay until I cleared the code in the computer. This code will also not out on the ck engine light.An easy quick test that will tell you your probelm. Next cold day dont plug it in. Turn the key on and run a scrwedriver across the 2 large terminals on the gp realy for 20 sec then try to start it.then you know if realy is not working, weither its bad or not getting the propper singnal some more testing will be needed. This will point you in the right direction. You can pm me if you want any more info. Its a fairly easy system.