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fuel pressure

Discussion in 'Truck & Equipment Repair' started by elite1msmith, Dec 27, 2008.

  1. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    i have a 95 chevy 3500 454 TBI, i donthave any fuel pressure up by the motor... i know the simple thing to do is test the pump ...but its raining , and i cant pull it in the garage...

    so give me a few pointers, is this electric fuel pump, or engine driven ? its a dump , so i cant pull it inside to see what the deal is

    i know it has a fuel relayand fuse, so i assume it has at least1 fuel pump

    i guess startwith that
     
    Last edited: Dec 27, 2008
  2. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    relay is good... and i jumped it , still got nothing.... anyhelp?
     
  3. mycirus

    mycirus Senior Member
    from Mass
    Messages: 589

    Is your fuel filter clean?
     
  4. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    we just bought the truck , so i have no idea... my guess is no

    i dont here the fuel pump powering up


    if BB is on? or anyone else, got wire colors for me to test power at the pump? and which line is the pressured line
     
  5. Spitz

    Spitz Senior Member
    Messages: 192

    The wires will be the two larger in gauge as they carry more amperage. Probably grey and black.
     
  6. bula_1984

    bula_1984 Member
    Messages: 45

    Did the fuel pump have a bad hum when it was running? If it did turn the key on and if you DO not hear the hum then you have a bad fuel pump. If you need to move the truck you can take a hammer and tap the bottom of the fuel tank and see if you can get the fuel pump running.
     
  7. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    we got the dump ned up in the air... so i have very easy access to the top of the tank at this point... jsut wish i could test the wiring first befire removing the pump
     
  8. bula_1984

    bula_1984 Member
    Messages: 45

    Turn the key on and you should have 12 v to the plug on top of the tank.
     
  9. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    4 wires at that plug
     
  10. bula_1984

    bula_1984 Member
    Messages: 45

    it should be the larger gauge wires. you can also do a google search to find out the wire colors. off hand I have no clue which wires they are. if you turn the key on and get no sound coming from the tank the fuel pump is probably bad.
     
  11. Spitz

    Spitz Senior Member
    Messages: 192

    Are you actually reading any of these responses to your posts? The two heaviest gauge wires. More then likely grey and straight black.. Usually purple and black with a white tracer is for the sender.
     
  12. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    yes i can read thank u


    they are all the same gauge , i figure 1 ground, 1 fuel supply line, 1 sender supply line, 1 sender return line... i jsutdont want to guess, and accidently apply power to the sender and blow it

    i dont knwo the colors , as its dark ouside, and1 am , but tommarow ill be sure to check

    no hum , but that also doesnt mean its getting power either
     
  13. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Gray is your 12V power wire.
    Black is your ground.

    Gray will only be hot for 2-3 sec after you turn the key on.

    Where's the FP relay located? '95 was a ******* year..does it have a fuse/relay box on the driver side inner fender with the FP relay located in there? Or is the FP relay on the passenger side on the firewall?

    Makes a difference as to how you diagnose it.
     
  14. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    B&B, the man


    fuel pump relay is located on the drivers side...heres the funny part, the fuel pump fuse, also located in that same box, was not installed... after looking at it, there arnt e ven contacts in that fuse area? so basicly its a dud spot.... and yeah i double checked

    in fact3/4 of the entire fuse box is unused, and there arnt even contacts in it
     
  15. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    See what I meant about the '95's? :D

    Start with your power and ground checks back at the FP and let us know what you come up with. Likely its just a dead pump..
     
  16. MAR4CARS

    MAR4CARS Senior Member
    Messages: 246

    Make sure you check the plug on the main harness coming from the truck FP harness we have found alot of those plugs go bad.
     
  17. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    B&B if it is a dead pump, do u have any tips for removing the old one... it all looks really rusted in place
     
  18. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Clean the area around the sender very well before you attempt any removal from the tank. This will keep any debris from falling into the tank. If it looks bad on top don't fool with trying to save the old sender assembly, replace it all. If the hoses look decent but they're just rusted to the sender fittings, just twist them off at the sender since you'll likely be replacing it anyway. This will save the lines for re-use.

    An aftermarket sender is ok but spend the money on a good pump, it's worth it.
     
  19. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    ok, will do


    i also have a problem , the motor seems to bog down heavy, if im light on the gas it goes jsut fine, but anything heavier on the pental and the motor just bogs out...its oundsas if its going to go , but never does.... i kinda was thinking the cat?
     
  20. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    More likley due to a low fuel pressure condition...hmm think it could be related to the current no start? :nod: