Maxxforce 13 losing fuel prime

Discussion in 'International Forum' started by gege71055, Nov 5, 2021.

  1. gege71055

    gege71055 Bobtail Member

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    Jul 12, 2017
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    I have a Maxxforce 12 that is losing fuel prime. I have to hand prime the truck every time I go to crank it. I’ve replaced the fuel filter house and prime pump. Someone told me their is a check valve behind the engine that would cause this is that accurate. Any suggestions would be appreciated.
     
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  3. Heavyd

    Heavyd Road Train Member

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    Feb 4, 2009
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    There is a check ball in the primer pump assembly, and actual check valve in the Davco filter/separator if your truck has one.
     
  4. ChuckMartel

    ChuckMartel Light Load Member

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    Jan 22, 2021
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    Check the fuel line between the Davco and the hand primer. They can get loose in the fittings.
     
  5. gege71055

    gege71055 Bobtail Member

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    Jul 12, 2017
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    I replaced the primer pump. Didn’t replace the davco filter I’ll try that.
     
  6. Grapevine

    Grapevine Bobtail Member

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    Nov 7, 2021
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    I just bought a prostar myself and having same issues.
     
  7. gege71055

    gege71055 Bobtail Member

    11
    3
    Jul 12, 2017
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    I bypassed the fuel water separator. And still having the same issue. Anything else I can check. On service Maxxforce the low fuel pressure is low 60psi. I think the spec is 80/90 psi correct?
     
  8. gege71055

    gege71055 Bobtail Member

    11
    3
    Jul 12, 2017
    0
    bypassed the fuel water separator. And still having the same issue. Anything else I can check. On service Maxxforce the low fuel pressure is low 60psi. I think the spec is 80/90 psi correct?
     
  9. Heavyd

    Heavyd Road Train Member

    7,292
    5,507
    Feb 4, 2009
    0
    Low pressure fuel pump could be worn out. To confirm losing prime, you would need to install a clear fuel line so you can see the line go empty where it connects to the engine. If the line goes clear after sitting for a while you still have a line problem somewhere such as at the tank or even a cracked pick up tube inside the tank. If the line stays solid with fuel but engine is still hard to start, I would say your fuel pump is worn enough it cannot draw fuel at crank.
     
  10. mixingconcrete

    mixingconcrete Light Load Member

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    Apr 14, 2019
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    Check on the bottom of your fuel tank to see if you have metal shavings. We had the same problem and our fuel pump was going out and our fuel tank had metal shavings on the bottom. We had to hand pump the primer every morning. After we replaced the fuel pump it fixed the problem. Went through 2 fuel pumps already in the last 5 years on our truck.
     
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