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In Tank fuel pump

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 90K5, Nov 8, 2000.

  1. 90K5

    90K5 1/2 ton status

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    I think my fuel pum is going out. Every now and then it will die, but come back. Sometimes it starts running rough like it will die and I just give it some gas and sometimes that helps. I have to drop the tank to change the fuel pump and I have a feeling that this is a PITA. Is it possible to use a fuel pump from a truck that goes on the fuel line? Would that work? That would be a lot easier than dropping the tank, obviously.

    90K5
     
  2. BurbinOR

    BurbinOR 3/4 ton status

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    I imagine you would have to remove your in-tank pump first, and modify whatever pickup/hose combo is in there, but YES, you can use a frame mounted pump. We did that on my Blazer for TPI and my builder has done over 25 TPI conversions, all with frame mounted pumps and filters. Makes it so much easier to change.

    <font color=black>'79 - 406 TPI -<font color=orange> K5#5 - <font color=blue>See it at---&gt;http://www.blazzinor.coloradok5.com
     
  3. 90K5

    90K5 1/2 ton status

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    Hmmm. so either way it sounds like I need to drop my tank...

    90K5
     
  4. CK5

    CK5 In my underwear Administrator Premium Member GMOTM Winner Author

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    dropping the tank is fairly easy, I did mine by my self, just make sure the tank is close to empty so it is light, disconect the wires, fuel lines etc and then lower the rear (two bolts by the bumper) part of the tank, I used a floor jack to catch the tank and then lower the back of the tank, you may not even have to drop the tank all the way. My stock pump lasted 10 years and 170,000 miles, in-tank pumps will last longer because they are kept cool being submerged in the gas. I installed a Walbro high-flow pump while I was there.

    [​IMG]
    5,000 Pounds of American Rolling Steel
     
  5. 87Blzr

    87Blzr 1/2 ton status

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    Do you remember when you did your pump? Is there a clip or anything that hold the wiring connection together at the sending unit? When I did mine all I did was make the connection through the sending unit and that was it. It seems there should be some sort of clip that hold the connection together but maybe I am being paranoid. I have this fear of the pump wiring coming undone at the sending unit because it doesn't seem like much is holding the connection together. Any insight as to how that connection is made and if I am missing something or worrying over nothing

    87 K5 Siverado, 68 SS 396 Camaro
     
  6. delta9blazer

    delta9blazer 1/2 ton status

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    <font color=red>WAIT!!</font color=red>
    don't drop your tank yet. i just had the same symptoms, and i got a new fuel pump. that wasn't the problem! and now i can hear the darn pump runnin' unless i have the stereo on! not real loud, but i never heard it before.
    change your cap and rotor. buy quality stuff, not from checker, or kragen or whatever. go to napa.
    i did that first, but bought crap(i didn't know it was crap). the problem stayed, so i chased it a looooong way. new fuel filter, pump, spark plugs and wires, etc. the truck finally died on the road, and a mechanic i know started back at the cap-n-rotor, and fixed it right off.
    it'll be a cheaper fix, and if it really is the fuel pump, you'll be ready for it at the firing line!

    <font color=purple>delta9blazer</font color=purple>
     
  7. 87Blzr

    87Blzr 1/2 ton status

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    Well if your not positive that its the pump you should first check the relay on the firewall. Jump it to power and see if you hear the pump come on. Always check that first.

    87 K5 Siverado, 68 SS 396 Camaro
     
  8. mudpuppy89k5

    mudpuppy89k5 Registered Member

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    About a year ago, my '89 ran rough and stumbled on the way home from work. Next morning same thing. Went out for lunch and it wouldn't start and I got to ride home in a wrecker. I sprayed starting fluid into the TBI and it cranked and ran for a second so I figured it was the fuel pump. I got an AC Delco pump at AutoZone. Unfortunately, the tank was 2/3 full at the time and that made it more of a PITA than it should of been, but with a floor jack it wasn't that hard. I'm don't remember for sure, but it seems like at the time I was surprised that there was not a clip holding the wiring to the sending unit, just a plug. If I still have the old pump, I'll look at it tonite.

    John Perry
    http://www.mudpuppy.coloradok5.com/
     
  9. 90K5

    90K5 1/2 ton status

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    i just changed the cap and rotor two days ago because I thought they were the problem. I aslo bought crap at AutoZone, but it made it run worse so I took it back and got some AC Delco stuff and it runs good, except when it dies. When you listen for the fuel pump coming on, is that the sort of buzzing sound you hear when you turn the truck off or before you turn it on? Is that good or bad??

    90K5
     
  10. DMK

    DMK 1/2 ton status

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    Yes, fuel pump will make buzzing sound.
     
  11. BurbinOR

    BurbinOR 3/4 ton status

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    Assuming you turn key on, but not start truck, the buzzing should last just a few seconds..........then stop. It is "filling" and pressurizing the lines. Figure if you are hearing it continually, maybe it is weak or the filter is plugged........

    <font color=black>'79 - 406 TPI -<font color=orange> K5#5 - <font color=blue>See it at---&gt;http://www.blazzinor.coloradok5.com
     
  12. 89K5

    89K5 1/2 ton status

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    Mine will buzz for at least 10 seconds after I turn the engine off. The engine hesitates like hell when cold. Could my pump be bad?
     
  13. DMK

    DMK 1/2 ton status

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    Yes or a clogged fuel filter. A dealer can check fuel pump pressure.
     
  14. backlash

    backlash 1/2 ton status

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    I believe the buzzing you hear is the pump returning gas to the tank. Least that's what I've been told.

    Ten seconds? Time it ... that's too long. Not sure what it means though.
     
  15. backlash

    backlash 1/2 ton status

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    Hey 90K5,

    My stock pump made a buzzing sound, but never really noticed it. Was quiet, I guess. When I replaced it... man did it piss me off! Eventually it quieted down or I got used to it.
     
  16. jarheadk5

    jarheadk5 1/2 ton status

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    To make the job easier in the future, you can cut an access hole in the floor above the tank so you can get to the pump/sending unit. A little creative sheetmetal work and some silicone and you're good to go!

    [​IMG] Semper Maintenance!
     

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