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7.3 turns but wont fire

Discussion in 'Ford Trucks' started by Maclawnco, Jan 1, 2013.

  1. Maclawnco

    Maclawnco Senior Member
    from OH
    Messages: 627

    We parked this truck after saturday's storm with no indications of any engine issues. Plugged it in like we always do when its done. We went to bathe it yesterday to find it wont start. We kept it plugged in and hooked up a battery charger. It turns over just fine but has a very, very hard time firing. When it does, it jumps around rpms for 10-ish seconds (500-1000 rpms) then dies. Mechanic said maybe gelled fuel but I dont think so as our CTD start just fine and were fueled at the same place/time. Any ideas guys? TIA
     
  2. goel

    goel PlowSite.com Addict
    Messages: 1,079

    First thing that comes to mind is a cam sensor. But I am not a mechanic, just a 7.3 owner. Replaced 2 on a truck so far.
     
  3. Raymond S.

    Raymond S. Senior Member
    Messages: 513

    Sounds like fuel. Just for kicks, throw a salamander heater on it to make sure it's getting heat. Also, are the glow plugs working? Could be glow plug relay.
     
  4. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Got oil? Needs oil pressure to fire injectors. Cam sensors go bad all the time too.
     
  5. jtslawncare

    jtslawncare Member
    Messages: 33

    yea I believe 500psi they need.. Id override the glow plug relay on top of motor with a screw driver for about 10-15 secs then have someone fire it..
     
  6. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Does thelug in heater work?

    Do the glow plugs work?
     
  7. dfd9

    dfd9 PlowSite.com Addict
    Messages: 1,475

    Cycle the glow plugs aboot 5 times. And leave it plugged in. If the battery is getting weak, throw a charger on it for 10 or so minutes.

    I'm in the weak glow plug relay camp.

    Look into Trombetta for a replacement. B&B gave me the part number and I have never heard a negative word about Trombettas. In fact, I got sick of the cheapies from NAPA and switched all mine this fall.
     
  8. Maclawnco

    Maclawnco Senior Member
    from OH
    Messages: 627

    The plug in works but I dont think the glow plugs work. Thx all for your help so far
     
  9. dfd9

    dfd9 PlowSite.com Addict
    Messages: 1,475

    Can you get it towed or pushed inside?
     
  10. snowyangel

    snowyangel Junior Member
    Messages: 29

    Mine runs rough as hell for 15 seconds if not plugged in, and has no power when on the pedal until its warmed up. Mechanic says it may be a sign that the HPOP is going to need replaced soon. He told me to just let it warm up good first.
     
  11. Maclawnco

    Maclawnco Senior Member
    from OH
    Messages: 627

    the truck would take 10 or more glow plug cycles this fall to start if it wasnt plugged in. So, we keep it plugged in all the time now and it had been starting just fine as it did when we started it before saturdays storm. We parked it after that plow event and now it wont start. I dont have any heated space left inside; its all full of salt now. The mechanic is going to try the cam sensor. Hoping this works.
     
  12. dfd9

    dfd9 PlowSite.com Addict
    Messages: 1,475

    Replace the glow plug relay first.

    It isn't the cam sensor.

    I guarantee it.
     
  13. allagashpm

    allagashpm Senior Member
    Messages: 703

    if you had trouble this fall as well then it is the relay. Happened to mine last year, anything below 35 she would have a hard time starting, if at all. Now that the temps are lower it will give you more trouble.
     
  14. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    If you have it plugged in and the block heater is working then you don't need the glow plugs. Check your oil level, remove and inspect fuel filter. Could be a weak cam sensor, rare but does happen. Is you EWL on? When you turn the key on does the temp gauge go up some? Can you hear the lift pump running?
     
  15. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    Check voltage on batteries do you see it drop down to 11 volt when turn on key for glow plug relay? Do you hear click from relay? If not I use biggest snowplow relay on mine no problem It was Trombetta for Boss snowplow.


    Leave plug block heater for about 5 hours did it start or rough idle? Sound like injectors issues. Do you have someone with scanner they could look at ICP pressure and IPR duty when crank.
     
  16. dfd9

    dfd9 PlowSite.com Addict
    Messages: 1,475

    Horse hockey.

    I have 4 7.3s. If the GPR is weak, they will not start no matter how long they've been plugged in and the temps are below 40ish.
     
  17. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    Well that shows how little you know. First a glow plug relay cannot be weak they either work or they don't. Second if it is plugged in and the block heater is working properly then the engine will already be warm soyou would not need a cold start assist( glow plugs). You do not need glow plugs to start or run a diesel. And for the record I have been a diesel mechanic for almost 20 years. What are your credentials?
     
  18. dfd9

    dfd9 PlowSite.com Addict
    Messages: 1,475

    I slept at a Holiday Inn Express last night.

    OK, I used the wrong term about the GPR's. I have had numerous go out the last couple years. I replace them, cycle the glow plugs and the non-starting issue goes away. All have had the block heater plugged in. The block heaters are functioning.

    I never said a diesel requires glow plugs, I also have 3 Cummins. I do know the 7.3s need them though.
     
  19. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    If you have them plugged in and you still need the glow plugs to start then you have other issues going on. We get 444s in here all the time for the same issue and rarely does it end up being glow plugs or relay. A 444 is a 7.3 with a mechanical fuel pump whereas ford runs an electric pump.

    I ran my 7.3 with a bad relay for almost 2 years because it was either parked in a heated garage or plugged in and it always started for me.
     
  20. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    A 444 is a 7.3?