Problem with Cummins N14

Discussion in 'Trucks [ Eighteen Wheelers ]' started by WildHog, Oct 14, 2011.

  1. WildHog

    WildHog Light Load Member

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    I have a weird problem with a 95 freightliner coe/cummins n14.
    Cranks fine cold, no smoke, runs perfect about 40lbs oil pressure cold.
    Revs perfect. Minutes later starts loping up and down and sometimes will clear out and run smooth and just die (or during lope will just die) as if the key has been turned off. Fuel pressure is good. No fuel leaks. No codes. After it dies, it will not crank again immediately. You have to wait 10-15 minutes and then it recranks and does the same thing all over again.
    Anyone?
     
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  3. Pablo-UA

    Pablo-UA Road Train Member

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    check tank breether
     
    jamespmack Thanks this.
  4. WildHog

    WildHog Light Load Member

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    Are you saying check Breather in tank?
     
  5. Pablo-UA

    Pablo-UA Road Train Member

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    yep/

    but it is not all. problem you got is related with fuel delivering. Yep, you measure pressure after start up, but try to keep gauge under hood and do the test ride, when you get your engine missing, pull over, open hood and check pressure. I usually use gauge with rubber hose and I put gauge under wiper blade to see pressure when I do the test drive.
     
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  6. blanco

    blanco Road Train Member

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    Pablo is spot on. I would also suggest changing all your fuel lines. 1995 was a long time ago and rubber does deteriorate.
     
  7. Heavyd

    Heavyd Road Train Member

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    When you say it will not crank again, are saying the engine won't fire, or won't turn over?
     
  8. Pablo-UA

    Pablo-UA Road Train Member

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    If no crank when hot it is bad starter....

    But I sugest after engine stalls, starter cranks engine, but no start....
     
  9. WildHog

    WildHog Light Load Member

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    I'm sorry, engine will not fire. It turns over fine.
    Fuel Pressure is about 130lbs at idle and the motor does not miss at all. I cranked it today let it idle for a minute or so and then took it up to 1500 rpms (smooth as silk) let fall back to idle and it died a few seconds after reaching idle just like the key was turned off.
    I guess it could be the pump or fuel pressure. Is there an easy way to take the ecm out of the equation?
     
  10. WildHog

    WildHog Light Load Member

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    I just found something new about this deal. Weird.

    After a few minutes of running fine the truck finally dies and won't start at idle, If I give the truck throttle and try and start it, it starts and runs fine above 1000 rpm but if you let it idle it dies immediately. It will not crank at idle but runs fine above 1000 rpm.
    What the heck? Throttle position sensor? Cam sensor? I don't think it's the ecm.
     
  11. Pablo-UA

    Pablo-UA Road Train Member

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    sometimes we have combination of problems. Engine stalls with bad fuel pressure but cant be restarted hot becouse bad starter, wires, batteries....

    It is wierd, but cold (not frozen down) N14 crancks better hot one!
     
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