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Gas gauge reads full all the time?????

This is a discussion on Gas gauge reads full all the time????? within the Technical / Maintenance forums, part of the General Discussion category; How would I fix this problem....

  1. #1
    Registered User 90Z71Stepside's Avatar
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    Gas gauge reads full all the time?????


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    How would I fix this problem.

  2. #2
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    Re: Gas gauge reads full all the time?????

    Sounds like you have the guage grounded.
    You need to check your wires.
    I think you can pull the plug on the tank/sending unit, and see what the resistance is. You will need a book to tell you what it should be between full and empty.
    If that reads good, start checking your wires.


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  3. #3
    Isn't so crazy afterall? crazyboy's Avatar
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    Re: Gas gauge reads full all the time?????

    wish mine was full all the time!

  4. #4
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    Re: Gas gauge reads full all the time?????

    Quote Originally Posted by crazyboy
    wish mine was full all the time!
    no doubt!
    2006 GMC Sierra SLT Crew Cab Z71

  5. #5
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    Re: Gas gauge reads full all the time?????

    That's a nice thought.
    I wish my Ford was full all the time. 10 miles a gallon sucks!
    Bad thing is I bought it cause I wanted a 3/4 ton to pull my trailer, but my 1/2 Chevy pulls better, and gets better mileage.


    03 Silverado ECSB, Dmax, Allison, 3.73 G80
    96 Silverado ECSB, 350, 4L60E, 3.73's Powertrax Locker
    05 Cavalier
    74 Corvette Stingray, 350, 4 speed
    49 F-1, flathead 6, 4 speed, 2wd, unknown rear end. Old rust bucket.

  6. #6
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    Re: Gas gauge reads full all the time?????

    Lucky you, mine seems to be stuck on empty
    1998 Chevy K1500- Used, Abused, and Sold 1989 Camaro Iroc-Z 5.0, auto....- Sold
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  7. #7
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    Re: Gas gauge reads full all the time?????

    My chevy is stuck about 1/4, my Ford is stuck past empty on both tanks.


    03 Silverado ECSB, Dmax, Allison, 3.73 G80
    96 Silverado ECSB, 350, 4L60E, 3.73's Powertrax Locker
    05 Cavalier
    74 Corvette Stingray, 350, 4 speed
    49 F-1, flathead 6, 4 speed, 2wd, unknown rear end. Old rust bucket.

  8. #8
    Registered User half ton z's Avatar
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    Re: Gas gauge reads full all the time?????

    I think you might have a broken wire. Most likely a rusted through wire terminal connection at the top of the sendind unit (on top of the tank).
    There will never be enough time untill there is no time.

  9. #9
    Registered User dave89iroc's Avatar
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    Re: Gas gauge reads full all the time?????

    unplug the plug to the sending unit and ground the purple wire, if it drops to E, you need a new sending unit
    Last edited by dave89iroc; 03-19-2008 at 08:49 PM.
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  10. #10
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    Re: Gas gauge reads full all the time?????

    If he has a broken wire it should drop to E.
    Like dave98iroc said, if you ground the guage it should peg F, if it goes to E the guage is bad. Unless you don't have power to the guage. I am still going to go with the guage being grounded.
    If you take the ground off and the guage drops, it should be a bad wire.
    Last edited by kcb37; 03-19-2008 at 11:12 PM.


    03 Silverado ECSB, Dmax, Allison, 3.73 G80
    96 Silverado ECSB, 350, 4L60E, 3.73's Powertrax Locker
    05 Cavalier
    74 Corvette Stingray, 350, 4 speed
    49 F-1, flathead 6, 4 speed, 2wd, unknown rear end. Old rust bucket.

  11. #11
    Habitual Troublemaker cancritter's Avatar
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    Re: Gas gauge reads full all the time?????

    gadge grounded or sending unit stuck in position
    [Stole/FOUND 13/03/08 :O)
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    07/ 6.7 Cummins..truck included
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  12. #12
    "the kid"
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    Re: Gas gauge reads full all the time?????

    mine reads 1/4 of a tank over and im out of gas before i get to the 1/4 tank mark . . . most people told me it was either a grounded guage, sending unit, the stance of my truck, or the floater was messed up . . . if i were you i would get a new guage
    1993 Silverado rcsb, hho injected, cold air, ceramic coated shorty headers, true duals into dynomax ultra-flow x, 2200 stall, shift kit, etc.
    1990 geo el cametro

  13. #13
    Registered User dave89iroc's Avatar
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    Re: Gas gauge reads full all the time?????

    Quote Originally Posted by kcb37
    If he has a broken wire it should drop to E.
    Like dave98iroc said, if you ground the guage it should peg F, if it goes to E the guage is bad. Unless you don't have power to the guage. I am still going to go with the guage being grounded.
    If you take the ground off and the guage drops, it should be a bad wire.
    on a pre vortec, open wire goes to F, shorted goes to E


    the newer ones go to E when open, because the BCM treats E as the default for any problem with the circuit
    ASE Master Certified Technician

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  14. #14
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    Re: Gas gauge reads full all the time?????

    Reviving this thread.

    I recently picked up an 89 Scottsdale w/the same problem. I tried unplugging the harness and grounded the purple wire and guage still read full so I'm thinking the sending unit is good. My odometer and trip meter is out so I'll check the ground on the gauge and see what happens. Any other input will be greatly apreciated!
    Last edited by DOLO; 06-02-2009 at 02:55 AM.

  15. #15
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    Re: Gas gauge reads full all the time?????

    Quote Originally Posted by dave89iroc View Post
    on a pre vortec, open wire goes to F, shorted goes to E


    the newer ones go to E when open, because the BCM treats E as the default for any problem with the circuit

    I have a pre vortec so I have an open wire? When you say open wire do you mean cut/broken but NOT grounded? I checked the purple wire at the connector before the fuel sending unit and had no power. I haven't checked it coming out of the gauge cluster yet though. I SHOULD have power coming from the gauge cluster right?

    Also, not sure if this is related as well but I think the oil pressure gauge is pegged as too.
    Last edited by DOLO; 06-02-2009 at 02:59 AM.
    1989 C1500, SCSB, 5.0, TH400

  16. #16
    Registered User dave89iroc's Avatar
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    Re: Gas gauge reads full all the time?????

    Quote Originally Posted by DOLO View Post
    I have a pre vortec so I have an open wire? When you say open wire do you mean cut/broken but NOT grounded? I checked the purple wire at the connector before the fuel sending unit and had no power. I haven't checked it coming out of the gauge cluster yet though. I SHOULD have power coming from the gauge cluster right?

    Also, not sure if this is related as well but I think the oil pressure gauge is pegged as too.
    yes, not much though, use a volt meter to check


    and yes, open is NOT grounded
    ASE Master Certified Technician

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  17. #17
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    Re: Gas gauge reads full all the time?????

    thanks for chiming in and clarifying that for me. Hopefully, I'll get some time this weekend to work this out.
    1989 C1500, SCSB, 5.0, TH400

  18. #18
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    Re: Gas gauge reads full all the time?????

    i have the smae problem and oil pressure is maxed also where are the grounds located do i have to take the dash all apart
    88 Chevy 2500 6" lift, 35's, 4.56 gears, disc brakes, headers, flowmaster 40, never ending project....

 

 

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