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Please Help!!!! Fuel Pump Wont Turn On

Discussion in 'The Garage' started by jimmy'sjimmy, Jan 27, 2007.

  1. jimmy'sjimmy

    jimmy'sjimmy 1/2 ton status

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    Ok its an 87 jimmy with a TBI 350 and cant get any juice to the fuel pump. checked all the fuses and connections. any ideas? what turns the pump on?:crazy: i working on it right now so any help will help
     
  2. crustydemon377

    crustydemon377 Newbie

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    check connection on back of alternator where power feeds back to battery, and check relay on firewall left hand side, and check ground back at pump.(use test light)
     
  3. Chaddy

    Chaddy 1/2 ton status GMOTM Winner

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    Are you sure the pump isn't trash?
     
  4. 4by4bygod

    4by4bygod 1/2 ton status

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    That would be my vote..I've never seen this problem not be the pump itself, and I've had the issue with a bunch of trucks we've owned..

    it's possible it isn't getting any power, due to a corroded contact at the tank maybe, but if you're going to drop the tank and check anyway, it makes more sense to change the pump too, just for the sake of security..On my 87 305/TBI K5, the pump failed after I had the tank down to fix a leak, so anymore I don't screw around.. I change everything..

    Tom
     
  5. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    The ECMB fuse controls the pump.. And it is turned on by the fuel pump relay, a small black box on your firewall above the heater... I've had them go, common, and thus why I keep a spare in the console...

    You can bypass all that and test the pump by running 12v directly to it back by the tank... Sometimes that wire has a disconnect there to facilitate that..

    If the pump doesn't respond, dropping the tank isn't as scary as many make it out to be... Floorjack makes it a pretty simple gig.. Heck, I've had mine out 2 or 3 times for various things...
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    You can make it even easier on yourself by running 12V from the battery straight to the fuel pump relay. There's one wire hanging off of it, that's the test lead.
     
  7. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Thanks for confirming that for me... I figured as much cuz it's refered to as a "priming" lead but had never actually powered it up...
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    I *think* you can actually do it from the ALDL connector as well, but I've not confirmed that. As I recall there is a terminal used for that feature.

    Anyways, you are correct however, in that even if the pump doesn't run bypassing the relay, the wiring/connections to the pump are still suspect, and powering the lead at the tank connector eliminates body wiring which COULD possibly be the problem. It doesn't seem to often be the problem, but would still be a possibility if the relay test doesn't get the pump to run.
     
  9. Storm Trooper

    Storm Trooper 1/2 ton status GMOTM Winner

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    I have that test lead hooked up to a switch on the dash so I can manually turn on the fuel pump if I need to. It makes it esy to pump gas to another truck that's out. Also keep in mind that since that lead (red) goes right back to the pump, you can put a meter on it and ohm it out. Good luck
     
  10. jimmy'sjimmy

    jimmy'sjimmy 1/2 ton status

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    Well we decided to just cut a hole in the floor above the fuel tank (too lazy) not enough time to drop tank. Ill always have easy access to the pump now. put in a new pump and also new oil pressure sensor. only thing i didnt do was look at the fuel pump relay because i didnt know where it was. that will be the next thing i check but not for a while. i live in dallas and the truck is is san marcos 3hrs away. after college i moved and the engine swap was not complete so i have been going down on weekends when i get a chance. ohh well ill get it done, thanks for the responses. my chiltons was nowhere to be found so i was stuck without info.
     
  11. goldwing2000

    goldwing2000 Guest

    As previously mentioned, the relay is mounted to the firewall on the right (passenger) side, near the heater box.
     

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