Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Fuel pump issues 454 TBI

Discussion in 'The Garage' started by TylerT, Apr 18, 2006.

  1. TylerT

    TylerT Registered Member

    Joined:
    May 30, 2005
    Posts:
    40
    Likes Received:
    0
    Location:
    OKC
    I put a new fuel pump in a couple of days ago. Haven't had a great deal of time to mess with the problem, other than take the fuel filter off. Here's what's happening, when I turn the key, the fuel pump does turn on, when I try to start it, it just cranks and cranks, the injectors are not spitting any fuel out. I took the filter off, and the line is not spitting any either. Is there something right off the top of anybody's head that might give me a little insight into this problem? I was very careful to connect the lines the correctly when I put the tank back in, I'd really hate to have to drop that big ol thing again...Thanks
     
  2. 1979jimmy350

    1979jimmy350 1/2 ton status

    Joined:
    Mar 24, 2004
    Posts:
    3,069
    Likes Received:
    0
    Location:
    Ann Arbor Mi
    check your fuel pump relay and your oil pressure sensor, if both are bad this could cause the problem. Are you getting fuel to flow when you first turn on the key? Under your hood there is a wire that is used for testing the fuel pump, it is a direct wire, hook up 12v to the wire and see if you get pressure
     
  3. mouse

    mouse 1/2 ton status

    Joined:
    Nov 10, 2003
    Posts:
    1,448
    Likes Received:
    0
    Location:
    Great Falls Mt
    For the initial start up you should get the 2-second prime like you mentioned.

    Are you checking for fuel pressure at the frame-mounted filter while the pump primes? If you get no fuel while priming, then most likely the issue is in the tank. The small rubber hose that connects the pump to the sender unit and sock would be suspect.

    The injectors should also be firing when you crank. The injectors always have 12 volts and the computer circuit provides a ground to get them to work. Make sure the computer has a good ground. There are a couple of ground wires on the passenger side of the engine. Look on the intake and rear of the passenger side head.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,982
    Likes Received:
    191
    Location:
    Roy WA
    I second Mouses comments. Make sure the injectors are pulsing.

    With no injector pulses, the ECM *probably* does not even know the engine is firing, or you've got a bad ground for the ECM. Injector pulse or not will tell you. You know the pump still works.
     
  5. TylerT

    TylerT Registered Member

    Joined:
    May 30, 2005
    Posts:
    40
    Likes Received:
    0
    Location:
    OKC
    Thank you all for your replies. I am not getting fuel at the frame mounted filter. I was as careful as I've ever been when I hooked up all the hoses and lines in the tank and on the pump, cause droppin' the tank I absolutely hate. I'll look into everybodies' suggestions today. Since am I getting no pressure at the filter, I should probably start at the back and work my way up? Or could this be the relay or oil pressure switch as well? Thanks again.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,982
    Likes Received:
    191
    Location:
    Roy WA
    As was mentioned, you only get the two second prime when you turn the key to run. If the ECM doesn't know the engine is cranking, you won't get any more fuel. It's priming, so why would it be the pump that's the issue? Start from the front back. (yes it can be a weak pump, etc., but you'd need to actually *test pressure*...at least you know the pump is running, but if the injectors aren't firing, it doesn't matter what the pressure is)

    I'm inclined to think you aren't getting an injector pulse, but force the fuel pump to run with the relay connector and test for fuel at the filter if you like. It's just cleaner/easier/more authoritative to check for injector pulse first.
     
  7. TylerT

    TylerT Registered Member

    Joined:
    May 30, 2005
    Posts:
    40
    Likes Received:
    0
    Location:
    OKC
    Okay, sorry for the dumb question, but how do you check for injector pulse?
     
  8. 1979jimmy350

    1979jimmy350 1/2 ton status

    Joined:
    Mar 24, 2004
    Posts:
    3,069
    Likes Received:
    0
    Location:
    Ann Arbor Mi
    hook up a test light to one of the injector connectors, then crank the engine over, if the light flashes you have injector pluse, that signal is opening and closing the injector
     
  9. TylerT

    TylerT Registered Member

    Joined:
    May 30, 2005
    Posts:
    40
    Likes Received:
    0
    Location:
    OKC
    Okay, I used a multi meter and got around 8.6 volts at the injectors. This is with a battery that has been cranking and cranking for a couple of days. I'm beginning to wonder if I have enough fuel in the tank..how much should there be to get the pump primed? Thanks to all for the help. I really appreciate it.
     
  10. 1979jimmy350

    1979jimmy350 1/2 ton status

    Joined:
    Mar 24, 2004
    Posts:
    3,069
    Likes Received:
    0
    Location:
    Ann Arbor Mi
    even thought you got voltage was the voltage plusing or constant, it the signal does not go on and off it is not working corectly
     
  11. TylerT

    TylerT Registered Member

    Joined:
    May 30, 2005
    Posts:
    40
    Likes Received:
    0
    Location:
    OKC
    It was pulsing.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,982
    Likes Received:
    191
    Location:
    Roy WA
    8.6 may not even be enough to fire the injectors or build much pressure with the pump...

    So you've got injector pulse, means the ECM knows the engine is cranking at least. Get the battery up to where it needs to be, then try forcing the fuel pump to run.

    You shouldn't need much gas at all, (on level ground) but if something is wrong in-tank (broken pickup, plugged up, etc) you might still hear it working, but have no fuel. Plugged fuel filter, etc.
     

Share This Page