Fuel Gauge doesn't work
Thread Starter
Junior Member
Joined: Aug 2013
Posts: 12
Likes: 0
Car: 1990 IROCZ
Engine: LB9
Transmission: T5
Axle/Gears: No RPO codes
Fuel Gauge doesn't work
Hello everyone, I just bought a 1990 Iroc yesterday and the fuel gauge is broken, the needle is always hanging all the way to the right side way past full. Anyone had this problem before or know what it might be?
Member
iTrader: (6)
Joined: Aug 2012
Posts: 466
Likes: 1
From: TN
Car: 1990 Camaro RS
Engine: L31
Transmission: 700R4
Re: Fuel Gauge doesn't work
I believe all the way to the full side is infinite resistance caused by either a broken wire or a bad sending unit. My 1990 RS had the same issue when I got it.
If you get under the car and follow the wiring out of the gas tank it will lead to a weatherpak connector. Unplug it and use a multimeter and measure the resistance coming from your sending unit. If it is infinite then your sending unit is probably bad. Sending unit replacement sucks... bad.
You can test your gauge by jumping the connector leading to the chassis, just DO NOT jump to the power wire for the fuel pump. It is in the same harness. The gauge should go to empty with the pins jumped.
If you get under the car and follow the wiring out of the gas tank it will lead to a weatherpak connector. Unplug it and use a multimeter and measure the resistance coming from your sending unit. If it is infinite then your sending unit is probably bad. Sending unit replacement sucks... bad.
You can test your gauge by jumping the connector leading to the chassis, just DO NOT jump to the power wire for the fuel pump. It is in the same harness. The gauge should go to empty with the pins jumped.
Supreme Member
Joined: Jun 2011
Posts: 2,036
Likes: 5
From: knoxville tn
Car: 86 IROC
Engine: 5.0 TPI
Transmission: 700-R-4
Axle/Gears: 2.73 open
Re: Fuel Gauge doesn't work
the fuel gauge grounds to the body under the left rear seat.it is possible that all you have to do is clean that ground and ,if you are lucky it will work again.good luck
Thread Starter
Junior Member
Joined: Aug 2013
Posts: 12
Likes: 0
Car: 1990 IROCZ
Engine: LB9
Transmission: T5
Axle/Gears: No RPO codes
Member
Joined: Jun 2011
Posts: 384
Likes: 0
From: Columbia, TN
Car: 1990 camaro rs
Engine: 5.0L 305 tbi
Transmission: 700r4
Axle/Gears: 2.73
Re: Fuel Gauge doesn't work
What if your fuel gauge reads empty at 1/4 tank and full way past the full mark. As in i run out of gas when it gets to 1/4 on the gauge and when i fill it up it goes past the F.
Supreme Member
Joined: Jan 2006
Posts: 3,341
Likes: 10
From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Top Fuel
Heres how to test the fuel gage.
Remove the sender wire going to the gage.
Tape the bare end of the sender wire and put it aside.
Use a potentiometer with a value of 100Ω or the closest you can find.
Connect one end the potentiometer to the gage from the location you removed the sender.
Connect the wiper of the potentiometer to ground.
Turn the key to RUN.
Slowly adjust the potentiometer from 0Ω to 90Ω.
If the gage is bad it will exhibit the problem you have.
If the gage is good it will display a smooth transition from one end of its range to the other.
Therefore the problem is with the sender.
You can use a loose potentiometer, or you can throw together a quick little panel like this one.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Rule Number 1 Is To Know Which Rules You Can Break
Remove the sender wire going to the gage.
Tape the bare end of the sender wire and put it aside.
Use a potentiometer with a value of 100Ω or the closest you can find.
Connect one end the potentiometer to the gage from the location you removed the sender.
Connect the wiper of the potentiometer to ground.
Turn the key to RUN.
Slowly adjust the potentiometer from 0Ω to 90Ω.
If the gage is bad it will exhibit the problem you have.
If the gage is good it will display a smooth transition from one end of its range to the other.
Therefore the problem is with the sender.
You can use a loose potentiometer, or you can throw together a quick little panel like this one.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Rule Number 1 Is To Know Which Rules You Can Break
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Junior Member
Joined: Jun 2013
Posts: 84
Likes: 0
From: Southwest Va.
Car: 1991 Formula Firebird WS6
Engine: 350 SB TPI
Transmission: 700R4
Axle/Gears: 3.23 Stockers
Re: Fuel Gauge doesn't work
If you figure out your sender is bad, I have a cheaper fix for that. Using your old float, and a generic sending unit, I have fixed mine. It takes a little time and some minor fabbing, but it works. I ordered an Equus 9982, fitted it and it works great! The unit is less than 20 bucks, and its a cheaper fix!
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