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gas guage broken please help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by roy87, Oct 14, 2006.

  1. roy87

    roy87 Registered Member

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    im not very machanicly sound an dmy gas guage just bounces up and downwhats wrong and how do i fix the problem:confused: :doah:
     
  2. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    If you do a search there's some very good threads on this. DYeager wrote up a very informative thread some time back.
     
  3. roy87

    roy87 Registered Member

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    thanks for the info
     
  4. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    just drive it til it runs dry then fil'er up...
     
  5. roy87

    roy87 Registered Member

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    i would normaly do that but i really don't feel like walking between gas stations any real advice or ideas on how to fix it
     
  6. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    probably a loose or corroded ground from your tank over to your frame, black wire.. You can check the gauge by grounding out the sender wire, which iirc is a tan wire with white stripe, fuel pump will be pink... when the sender wire is grounded, the gauge should pin to full, if not there's a prob with the gauge... If it pins, the prob lies in the sender connections, ground or sender itself...
     
  7. roy87

    roy87 Registered Member

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    thanks alot i'll give that a shot and see how it works. do you think it could possibly be the float?
     
  8. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Actually it sounds more like a connection, ground or sender. Or the gauge... Float sender would be most unlikely of all for a bouncing around condition..
     
  9. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    usually when a float goes bad it's because its soaked up and full of fuel and doesnt register properly, a bouncing gauge can be a bad sender though, i had an s-blazer with a bad sender, there was 2 tabs that rode along a resistance bar kinda thing and one broke off causing the sender to make the gauge bouncy... (re read my post here and sing "im bossy") LOL
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Bouncy gauge is not caused by the sender. The reading "damping" (why it doesn't fluctuate quickly as you accelerate, corner, up or downhill, hit bumps, etc) is handled in the gauge itself. The float always moves, very easily, and the only reason you don't see that movement constantly is that the reaction/interpretation of the float/rheostat in the tank is slowed down by the gauge. This is also why the GM manual states that you need to give the gauge time to respond when testing the fuel gauge circuit operation. There are no electrical components (carbed gas engine) on the sender other than the rheostat that is actuated by the float.

    Even grounding or breaking the ground of the gauge sender wire does not peg a fuel gauge instantly, given that everything is working correctly in the first place.

    Now of course, as soon as you make an authoritative statement like that, for some reason or another it will turn out to not be true. :) However, there are likely other issues as well, the fuel tank gauge circuit is a common "failure point" in these trucks.

    But, even if you pull the sender, you can likely clean it up. Never hurts to touch up the sender ground either.
     
  11. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    mucho agreed on the cleaning things up statement.. never hurts to have good, clean, new grounds..
     
  12. roy87

    roy87 Registered Member

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    awesome guys thanks for the help i'm not very sound when it comes to mechanics and all this stuff so i'm looking for the ground thats gona be on the tank its self? and i need to make sure that it is geting grounded and also clean it off right.
     
  13. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    yeah, it runs from the frame over to ring that retains the float sending unit and pump down in the tank.... Unfortunately the tank needs to be dropped to check your 2 connections on the tank, sender and ground... You can check the ground to frame without dropping the tank... If by chance you have a 3" bodylift, sometimes you can inspect those connections on top of the tank without dropping it...

    When I check the gauge by grounding the send wire, I'll usually just cut it in front of the tank, ground it to frame.. then you can splice it back together..
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Don't you have a connector on the send wire?

    Even my carbed setup had a single prong connector, you could just disconnect it and stuff a piece of stripped wire in there to touch to ground.
     
  15. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Mine had been replaced with a butt connector at some point.. :doah: Makes sense that one was there....

    So I just snipped it close, removed thiers and put my own in... :haha:
     
  16. roy87

    roy87 Registered Member

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    sounds good i'll try that this weekend and let you know how it goes thanks for the help. i'm going to have to drop the tank because i don't have a body lift at all
     

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