C15 starting issues.

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by 99sterlingdump, Jul 26, 2021.

  1. 99sterlingdump

    99sterlingdump Bobtail Member

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    I just purchased a 2005 Pete 379 with a twin turbo c15. The problem is it will not start without a little ether. I’ve read several blogs about changing the check valve on the filter housing, and I changed the one that is part number 281-2725 with no luck. When I push the hand primer in, I can hear the fuel going back into tank and it never gets hard. I’m thinking this is the issue and if so what do I need to replace?

    the filter on the block has been replaced (secondary I think) I’m going to replace the one on the frame tomorrow. The old filter was painted over so hopefully they can look up part number by the vin
     
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  3. lester

    lester Road Train Member

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    Primer pump should get rock hard. It could be bad and leaking air, easy enough to replace. I'd guess you changed the wrong check valve. I think (think) there are 2 on the filter housing. I'd have to look at one. Just pull it all apart and see and replace o-rings if they look bad. Do you have a fuel pressure gauge?
     
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  4. Oxbow

    Oxbow Road Train Member

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    It is unlikely but possible that one of the little check valves in the primer pump has flipped. I have seen this happen twice on B models. It doesn't cost anything to pop it off and inspect the two little check valves.........if they look identical one has flipped over. Then it's just a matter of figuring out which one. I know it is a long shot, but it's free to check and eliminate the possibility.
     
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  5. skallagrime

    skallagrime Road Train Member

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    Step 1, if you have a fuel restriction gauge (usually a small tube going up to cab from water seperator), cap it off, see if it goes away. That line gets brittle and cracks introducing air, ESPECIALLY if youve done any work behind the dash recently

    Step 2, IMPORTANT, KEEP THAT CAPPED OFF.
    Cap off one tank return and pull line, pressurize your tank to 5-6 psi, follow your pull lines (larger dia hose), check for deisel leaks. If you find one, its introducing air preventing the pull from keeping primed. Solution, replace all fuel lines, reason, if one went, the others arent far behind.
     
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  6. 99sterlingdump

    99sterlingdump Bobtail Member

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    Yes I was thinking it would get hard but when you push the primer you can see and hear the fuel going back Into the tank. Seems to me it would be a check valve but the one I replaced is the one that is on the “to tank” side. I read somewhere that it was common to go bad and I told Peterbilt the part number I read on forum and they said it was the correct one. Hopefully someone will chime in who knows all about the filter housing. I don’t believe it’s a bad primer because it is clearly moving fuel.


    No I do not have a gauge yet
     
  7. skallagrime

    skallagrime Road Train Member

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    Bottom or top fuel pulls? If top, pickup tube in tank could be cracked too.

    And fuel restriction gauge is overrated if youve got a good ear and pay attention to your motor, most people with all the gauges just ignore em anyway, many are only helpful for people with deeper knowledge and diagnostic experience than for instance myself, and im not actually that shabby at figuring out whats wrong with at least MY truck
     
  8. 99sterlingdump

    99sterlingdump Bobtail Member

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    What do you mean by bottom or top pulls? The returned fuel was coming in at the top of the tank
     
  9. skallagrime

    skallagrime Road Train Member

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    Then the primer pump is pumping the correct direction

    By top pull i mean, where does the fuel TO the engine pull from? Is that line attached to the Top or bottom of the tank?

    The fact that you have fuel pouring back to tank from the return line is a sign that your return check valve isnt right, i get that you replaced it, but it shouldnt be pushing fuel back to the tank till close to 55 psi. Replace it again, theyre cheap.
     
  10. lester

    lester Road Train Member

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  11. skallagrime

    skallagrime Road Train Member

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    Return check valve, what my stylus is pointing at do it again

    20210727_001106.jpg
     
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