Close



Results 1 to 23 of 23

Thread: fuel gauge

  1. #1

    Default fuel gauge

    Put a new sending unit in tank as the other one was broken in half, but the gauge still doesn't register, Is there an easy way to test the gauge? How often does the fuel gauge actually go out on these?

  2. #2
    Moderator wraithracing's Avatar
    Join Date
    Jun 2010
    Location
    Grand Junction, CO/RR TX
    Posts
    12,684

    Default

    1979-1986 Mustang/Capri Fuel Level Sending Unit Ohm Readings are approximately 73 ohms empty and approximately 10 ohms full. So you could use a meter and apply current to the gauge to test if it is operating properly. Good Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Ongoing RestoModification
    1984 SVO Awaiting Restoration
    1986 GT Wrecked by PO, but still want to save!

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Underway
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  3. #3

    Default

    I've seen some that acted "weird" but never seen a failed one.

  4. #4
    Moderator wraithracing's Avatar
    Join Date
    Jun 2010
    Location
    Grand Junction, CO/RR TX
    Posts
    12,684

    Default

    Quote Originally Posted by homer302 View Post
    I've seen some that acted "weird" but never seen a failed one.
    I agree that I have seen many act "weird" I do believe I have had at least one or two that didn't seem to work at all over the years, but definitely the exception to the rule. More often than not the sending unit or the wiring seems to be the issue for me.

    Also make sure that the nuts on the backside of the cluster are tightened properly. If not you don't get good contact with the circuit board and the gauges either don't work or act "weird". Just had that with my buddy's 86 SSP, the tach wasn't working and we couldn't figure out why. Finally realized that he had removed the gauges to clean them and didn't tighten the three nuts on the backside enough for good contact. A quick tightening and suddenly we had a tach again.
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Ongoing RestoModification
    1984 SVO Awaiting Restoration
    1986 GT Wrecked by PO, but still want to save!

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Underway
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  5. #5

    Default

    Thanks I guess I will take it apart and see if I can figure it out

  6. #6

    Default

    Turn on the ignition and unplug the sender connector, the gauge should go to empty, ground the wire and the gauge should read full. That will tell you if the wiring and the gauge is OK.

  7. #7

    Default

    I had a float come off an original 86 gauge sender once. No more gas gauge!

  8. #8

    Default

    Quote Originally Posted by erratic50 View Post
    I had a float come off an original 86 gauge sender once. No more gas gauge!
    Right, but there was nothing wrong with the gauge, which was the question. Fuel sender is almost always the issue.

  9. #9

    Default

    Quote Originally Posted by homer302 View Post
    Right, but there was nothing wrong with the gauge, which was the question. Fuel sender is almost always the issue.
    Unless the wiring back by the tank gets messed up (which happens fairly often) it’s likely the sending unit. Very likely not the gauge. The circuit boards on the back of the cluster like to fail too.

    I would be surprised if it’s the gauge.

  10. #10

    Default

    If a car sits for a long time, the sending unit can corrode. I clean them up with electrical contact cleaner if they are really crust then brush it off and rub it lightly with a rubber eraser.

    I have had two broken lying in the tank. One car sat on a field for about 15 years due to an electrical fire before I pulled it out of a feild.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  11. #11

    Default

    Could a bad or unplugged anti slosh module cause the gauge to not work?

  12. #12

    Default

    Where is that antislosh at? My gauge is insanely slow...
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    Hooker Super Comp Shorty Equal Length Headers
    GT40 heads, Edelbrock 3721, K&N filter in stock dual snorkel,
    Comp cams XE254H, hypereutectic pistons, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace
    3.73 rear. CS5 225/60/15 on 10 holes (street) Federal 595 rs-rr 225/45/15 on 10 holes (race)
    Everything else stock and fully functional.

  13. #13

    Default

    behind the glove box.

  14. #14
    FEP Power Member
    Join Date
    Nov 2007
    Location
    San Mateo, CA
    Posts
    1,662

    Default

    I don’t recall seeing an antislosh circuit on the early Foxbody. The aero nose cars have one and the circuit is reversed.
    Fox Body/3rd Gen MCA Gold Card Judge
    84 SVO 24K miles, 85 Mclaren Capri Vert. 84 GT Turbo Vert.
    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert,
    03 Mach 1 7900 miles, 74 Mustang II, 69 Mustang, 67 Mustang, 14 Mustang CS/GT,
    15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  15. #15

    Default

    back... from dead
    my fuel gauge is stuck on empty somewhere I heard that could be a gauge or antislosh, but I didn't think 86's had one, unless it is the unit behind the glove box?
    I had put a new sending unit in last year, but during the rebuild process I can't for the life of me remember if it worked, which is annoying as all...

  16. #16

    Default

    while this zombie is shambling... My gauge is still very sluggish and now the 'low fuel' led is stuck on. I wonder if the two are connected?
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    Hooker Super Comp Shorty Equal Length Headers
    GT40 heads, Edelbrock 3721, K&N filter in stock dual snorkel,
    Comp cams XE254H, hypereutectic pistons, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace
    3.73 rear. CS5 225/60/15 on 10 holes (street) Federal 595 rs-rr 225/45/15 on 10 holes (race)
    Everything else stock and fully functional.

  17. #17

    Default

    Pull the circuit at the rear of the carr and inspect.

    My 86 has a harness with gauge wires and fuel pump electrical that goes from each ..... the gauge and the pump .... down to one plug that plugs into a connector on the body harness.

    I've had corrosion inside of this harness connector before. I guess driving a four eyed fox every day on the midwest roads for 18 years tends to cause some corrosion. Once the corrosion caused my fuel pump to stop working. Another time I had corrosion inside of this very same harness connector cause my gauge and low fuel light to into a state of always reading empty with low fuel. So basically they stopped working.

    If I remember correctly what you end up having back there is effectively a low voltage power source wire and a lead that if connected would complete the circuit and run the gauge up to full. the low fuel light is simply there if more than a set amount of resistance is there. Having a low fuel light that's always on suggests the circuit always sees too little current for whatever reason.

    I would not dead-short the leads for more than a few seconds as it may burn something up, but you sure could add a 10 ohm resistor back. Don't have a resistor laying around? No problem. Take 3 old speakers and wire them in series. 4 ohms per speaker ... you have 12 ohms which is good enough for testing. Provided the speakers work they can carry plenty of current for this.

    You should see the gauge go up somewhere at or near full. If you don't then there is a problem with the gauge, the wiring, or the cluster itself.

  18. #18
    FEP Senior Member liv2roc's Avatar
    Join Date
    Jul 2009
    Location
    Cherryville n.c.
    Posts
    707

    Default

    mine stopped working so I replaced it a few years ago with one from advanced auto "big mistake" now it reads all over the place and low fuel light come at a half tank sometimes so I just reset my trip and refuel at 175 miles or close to it.

  19. #19

    Default

    How do you access that connector? I see the two wires heading down through the trunk but under that they just keep on going and out of reach.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    Hooker Super Comp Shorty Equal Length Headers
    GT40 heads, Edelbrock 3721, K&N filter in stock dual snorkel,
    Comp cams XE254H, hypereutectic pistons, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace
    3.73 rear. CS5 225/60/15 on 10 holes (street) Federal 595 rs-rr 225/45/15 on 10 holes (race)
    Everything else stock and fully functional.

  20. #20

    Default

    Quote Originally Posted by liv2roc View Post
    mine stopped working so I replaced it a few years ago with one from advanced auto "big mistake" now it reads all over the place and low fuel light come at a half tank sometimes so I just reset my trip and refuel at 175 miles or close to it.
    yep, fill her up and reset the trip, been doing it ever since I've had this car

    Brant

  21. #21

    Default

    So my gauge worked today until I got to the gas station turned it off filled up and it didn’t work again��

  22. #22

    Default

    In college I had an ‘86 carb 4cyl that the previous owner had run without oil.
    Me and a buddy swapped in an efi 3.8 from a t-bird in the junk yard.

    I used an aero car fuel tank to get the electric pump but the fuel gauge worked backwards. It would read empty until you were almost out of gas. If the low fuel light ever went off you’d better find a gas station quick!

    Only problem I ever had was when I was designated driver and told my friends they had to chip in for gas when the car started showing a full tank!


    Sent from my iPhone using Tapatalk

  23. #23

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •