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Help, Fuel pump prob

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by badfish4tail, Apr 18, 2005.

  1. badfish4tail

    badfish4tail 1/2 ton status

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    Okay on my way to work today my 91 k5 just died. When i got the rig towed back to my house i noticed It has plenty of crank but isnt firing up. I checked all the fuse's and they are all good. I did notice however that my fuel pump wasnt making its usual humming sound for the 3-5 seconds when the key is in the run position or just after you turn the engine off. Before i try replacing the pump i just wanted to see if there might be something i need to check first. Just got done topping off the tank the day before :mad: if there is nothing else please let me know and i will have to burn a saturday dropping the tank and replacing the pump :( ....thanks
     
  2. spearchucker

    spearchucker 1/2 ton status

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    Make sure the pump is getting power. You can disconnect the plug on the driver's side just before the tank and check to see it has 12V on one of the wires in the connector. If it doesn't have power then it could be the fuel pump relay.
     
  3. sweetk30

    sweetk30 professional hooker Premium Member

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    i am in the auto biss and it never fails . fill the tank to the top and whamo the pump is dead. i hate that. 1st check to see if there is power at the pump conection. 2nd check to see if good ground. 3rd if both are bad then other problems. if good then pump is bad. and fyi for ya average pump life is about 80-90k miles. also try hitting the bottom of the tank and haveing someone crank it at the same time it works sometimes . and that is a bad pump also. and last but not least need new fuel filter for the new pump. thay hate to push threw a pluged filter it will be the quick death of a new pump if that is the case. have fun and be safe under there.
     
  4. gone huntin

    gone huntin 1/2 ton status Premium Member

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    AMEN, almost every pump that I replace is in a full tank of gas, most are towed in from the gas station where they just filled them up. :screwy: :dunno:
     
  5. tlarsw

    tlarsw 1/2 ton status

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    pump

    Also, if you have an oil pressure sensor (there are two) fail this can cause no power to pump.

    Had it happen on an 88 Blazer. Hot wired the pump to ignition and I was in business.

    If it's the pump. PM me, I got one for cheap.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    You can force (test) the pump to run via the lone connector in the engine bay off the fuel pump relay IIRC.
     
  7. k20

    k20 3/4 ton status

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    Yep, should be a red wire, with a connector, stick a wire in that, run it to the positive battery post, and listen for it running. If its makin noise but doesnt sound like its pushing fuel, make try takin loose a fuel line, hit it real quick, and see if it shoots fuel out. If its makin noise it may just be locked up and kinda making a buzzing/grinding sound and not pumping fuel.
     
  8. shane74

    shane74 1/2 ton status

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    Yes you can. It's the red wire on the relay that's not connected to anything. Run a hot lead to it and if the pump is good, it will fire up. My relay went out in my '87 burb twice.
     
  9. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Fuel pump relays are notorious for going bad on GM vehicles. Check that first for 12V and if it has power then check for 12V at the pump connector and if good then replace pump. If it is the pump make sure you replace the sock attached to the pump as well as the fuel filter on the frame rail.
     
  10. mikayak390

    mikayak390 Registered Member

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    hi

    if it is the pump they are cheap, like $30. Bad news is its a PITA to get out. Have to drop a 32 gallon fuel tank full of fuel and usually the bolts are rusted. I cursed at mine for 3 hours just to get the skid plate loose.

    Then called a friend for suggestions. I still owe him a beer for this. Took 20 minutes and did not have to drop the tank.

    take an old towel or some rags soak them in water and stuff them between the top of the fuel tank and the body. Then take a small drill like 1/4 or smaller. Climb into the bed and try to get about where the fuel sender is. Drill a small hole. Go slow you want to go through the sheet metal of the floor, Not into the tank!!

    The wet towel collects any shavings and kills any possible sparks from the drill.

    The hole lets you peak down there and verify you are near the fuel sender. It also gives you a place to slide a small metal cutting jig saw blade in to start your cut.

    Again keep the towel over the fuel lines and the tank. Carefully cut a window into the floor about 9 inches or so right above the sender.

    Pop out the sheet metal from the bed and you have instant access to the fuel pump.

    Of course if your like me the sender was also rusted, and had to be special ordered, but hey its easy the second time.

    Oh when you are all done I used two small home depot hinges mounted in the valley of the bed to re-install the old sheet metal as a "door" Used a small latch on the other side. If you do it right all the screws on and the hinge are in the valley of the bed. basically they sit below the higher ridges, so you can still slide heave things in with out catching them.

    If you ever have problems again its easy to get to, and if you get a tank of bad gas, or some other problem its easy to pump out. never mind the lach of stress from trying to deal with a few hundred pounds of gasoline and getting your hands between the tank and body to tighten the lines up.

    Its not a method for everyone, but if your carefull its fairly easy. I think its a lot less dangerous than crawling under the truck trying to fight with a heavy rusted tank and fuel spilling everywhere. Just my opinion.
     
  11. badfish4tail

    badfish4tail 1/2 ton status

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    Okay here is what i have done so far....replaced the fuel pump,strainer,filter,relay,battery and to top it all off the damn starter. :mad:
    I still have one BIG prob. My truck wont start!!! It will crank but it will not fire up... I am very very frustrated.... I checked the cap, rotor, wire's and plugs....What should i do next...i am thinking of actually towing it to a repair shop....HELP!!! :eek1:
     
  12. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Do you have spark, and fuel spray? Maybe your ECM is bad. How about the ignition module?
     
  13. gone huntin

    gone huntin 1/2 ton status Premium Member

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    Yep, you need to check that module.
     
  14. badfish4tail

    badfish4tail 1/2 ton status

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    okay i got the truck to start and run this morning for about 20min.
    but now the "ECMB" fuse keeps blowing...what is the ecmb? i know its a computer but wicj one?
     
  15. blazenwhip

    blazenwhip 1/2 ton status

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    I had a similar problem. It sometimes would start. The problem was the fuel pressure regulator on the TBI. Autozone sells a replacement kit for about 25-30 bucks. Let me know if this works.
     

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