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More ???? on a TBI truck i just got

Discussion in 'The Injection Section' started by 84CUCV, Feb 27, 2007.

  1. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    Well, just got a 87 with a 5.7. Cant get it to fire up. Has spark. i cranked it and my friend said he could see the inside of the tbi wet, so it has fuel. its a duel tank truck, one tank is out and the lines are just laying there. Would that do anything to keep it from fireing? I thought if i put it on the right tank it would not matter. hard to read the switch its very faded. So what am i missing? as always thanks for the help
     
  2. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    At start up are you hearing the pump run before you fire it up? You should do for a few seconds. When cranking , the injectors throw a good amount of fuel out, you should be able to see that clearly.
     
  3. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    OK then maybe my friend was wrong. I did not hear a thing. I didnt know the wes a pump you could hear. Guess i not getting fuel. crap thanks for the reply
     
  4. 88-383

    88-383 1/2 ton status

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    Yup, as long as it's got fuel,spark and compression it has to fire!
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Not if someone has the timing so far off or lord help 180* out.

    Seriously though, when the key is toggled to the on position you should be able to hear the fuel pump run for 2 seconds then stop. If not i would first check the relay on the passenger side firewall.
     
  6. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    OK where is the fuel pump anyway? thanks
     
  7. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Like 4x4 says, on the firewall. It's just above and to the left (looking into the bay from the front) of the aircleaner. Black plastic relay cliped to the wall.
     
  8. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    OK i got it thanks. Now i have a place to start.
     
  9. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    do any off you think the two tanks matter? i am thinking about running one for now and getting a fuel cell down the road. thanks
     
  10. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Tanks don't matter, the switching valve changes which fuel pump and sender to use. Actually, i suppose the switching valve could be bad and that's why your pump doesn't work.
     
  11. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    OK do you know how to test it by some chance?
     
  12. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    Hi guys, got to check the truck out a bit. In this pic is this what you guys are talking about on the left of the air cleaner? put the key to the run spot and it clicked. so i guess its good? thanks for the help

    DSC02671.JPG
     
  13. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    that's the fuel relay. You can power that red wire to run the relay for test. Manual tells you about it. I've never done it but I believe it bypasses everyhting and powers up your pump direct.
     
  14. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    ok thanks
     
  15. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    is there a way to test the relay?
     
  16. dyeager535

    dyeager535 1 ton status Premium Member

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    Yes. If it runs with 12V to the red wire, and doesn't without 12V to it, the relay is faulty.
     
  17. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    thanks
     
  18. dyeager535

    dyeager535 1 ton status Premium Member

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    I better clarify though:

    The oil pressure switch will allow the truck to run even if the relay is dead. "It running" that I refer to, is the fuel pump, not the engine.

    If the relay is dead, starting the engine should take a bit longer as the oil pressure needs to build up a bit before the switch closes. If you power the relay (assuming it's dead) on the red wire before starting, that "lag" would be eliminated.
     
  19. 84CUCV

    84CUCV 3/4 ton status Premium Member

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    think i got it thanks not to good with wireing yet.
     

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