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where the h**l is my fuel pump relay??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by muddysub, Aug 29, 2004.

  1. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    where the h**l is my fuel pump relay on my 1989 TBI 350 suburban...

    i replaced my injectors, fuel filter, rebuilt th TBI hooked everything up and still no fuel. none. at all. so im curious as to wether or not the fuel pump works now. when u hit the key it makes noise but not as much as most GM fuel pumps, or as much as i remember it making. so im hoping the relay is bad, though i doubt it. it looks like the suburban may be getting a trap door installed on the floor in the rear of the truck. lol
     
  2. Jays Beast

    Jays Beast 1/2 ton status

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    On the passenger side fire wall, above the valve cover. It is oval shaped cylinder. A new one is about $10 would suggest replacing it, if you do replace the fuel pump. When I replaced my fuel pump, not even a week later the relay was dead.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Fuel pump relay is bypassed if the system sees approx. 5 psi oil pressure...
     
  4. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    IIRC there are 2 cylindrical black boxes on the fire wall above the pass valve cover. which one is it?
     
  5. Jays Beast

    Jays Beast 1/2 ton status

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    /forums/images/graemlins/dunno.gifI only have one relay there, not sure what the other one is for.
     
  6. Jays Beast

    Jays Beast 1/2 ton status

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    Looked it up in the Chevy service manual, shows the fuel pump relay on the right if you looking at the firewall. Says the other one is either a fuel pump fuse(H) or a fuel test connector(K) depends on the engine code H or K. I can't say for sure since mine does not have anything there. /forums/images/graemlins/thinking.gif I might have to go look around and see if there is a unused harness connection near there.
     
  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    you truck is a factory 3/4 isn't it?

    The other relay is the kick down for the TH400.
    If you hear the noise you got fule pressure. Have you got spark? spark and injector timing are off the same pickup. Usualy if you got no fuel and its lack of injector trigger then you got not spark as well.

    Got any codes.
     
  8. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    yeah, 3/4 ton. so its the kickdown for the th400... thanks.

    i got spark just no fuel, you can look at the injectors and see that nothing is coming out of them when you crank it over. but if you spray carb cleaner or something down the throttle body it'll run til you stop spraying it.
     
  9. Hossbaby50

    Hossbaby50 3/4 ton status

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    Did you check to see if the injectors are getting pulsed to fire? You can use a Noid light to figure out if they are firing. Might check the ignition module.

    You can use a test light to see if they are firing too but you almost need 3 hands to pull that one off and you do need 2 test lights.

    Harley
     
  10. 88sub4x4

    88sub4x4 1/2 ton status

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    Just unscrew one of the fuel filter lines, and turn the key on and see if fuel spills out. Just be careful with the spilled fuel.
     
  11. SHAWNSTER

    SHAWNSTER 1/2 ton status

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    when my blaze broke down i swore it was the pump and after pulling tank and repalcing pump it was the damn relay- /forums/images/graemlins/angryfire.gif and i had forgot to test it first-6 hours later and $11 it was fixed
     
  12. muddysub

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    yeah ive had the lines off and othing is getting up to the TBI, well ill replace the relay first then.
     
  13. Thunder

    Thunder 3/4 ton status

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    Have you checked the following:
    Dist module
    Magnetic pickup coil
    Oil pressure switch
    Any of these,if bad. Will not allow the injectors to work .
     
  14. 88sub4x4

    88sub4x4 1/2 ton status

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    Check to see if you are getting power and ground at the pump.
     
  15. blazd88

    blazd88 1/2 ton status

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    [ QUOTE ]
    Have you checked the following:
    Dist module
    Magnetic pickup coil
    Oil pressure switch
    Any of these,if bad. Will not allow the injectors to work .

    [/ QUOTE ]
    yeh the same thing happened to me and it ended up being the distributor module most parst stores will check them for free.
     

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