Wacky fuel guage... sending unit?
Thread Starter
Junior Member
Joined: Mar 2013
Posts: 67
Likes: 0
From: Cary, NC
Car: 1986 IROC-Z/28
Engine: LB9 TPI
Transmission: 700r4
Wacky fuel guage... sending unit?
Hey!
I have an 86 TPI iroc, and the gas gauge is completely out of whack. I fill her up yesterday, 5 hrs later im 'out of gas' so I keep going for 2 hrs THEN fill up and she only takes 8 gallons! WHAT??
So does this sound like a sending unit problem? It will NEVER go to full, and will go to empty when on a half tank unless I accelerate (when i accelerate the gauge goes to around where it has fuel) and then past a quarter tank its a guessing game.
Any help? Kind of a big problem thanks.
I have an 86 TPI iroc, and the gas gauge is completely out of whack. I fill her up yesterday, 5 hrs later im 'out of gas' so I keep going for 2 hrs THEN fill up and she only takes 8 gallons! WHAT??
So does this sound like a sending unit problem? It will NEVER go to full, and will go to empty when on a half tank unless I accelerate (when i accelerate the gauge goes to around where it has fuel) and then past a quarter tank its a guessing game.
Any help? Kind of a big problem thanks.
Supreme Member
Joined: Dec 2012
Posts: 1,356
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From: northern VA
Car: 88 Sport Coupe Camaro
Engine: V6 2.8
Transmission: Borg-Warner T-5
Axle/Gears: RPO/GU6: 3.42
Re: Wacky fuel guage... sending unit?
To test the gauge, all you need is a specialized dealership tool, part #J-24538-A.
You've got one those, right?
In all likelihood, the gauge itself is failing.
...which is probably better than having "nuts loose" (see diagnotic Step 6).
The correct fix would be replacement of the OEM gauge with a brand-new OEM gauge, which is currently made out of unobtainium.
Hawks will sell you used gauges.
http://www.hawksthirdgenparts.com/ca...26-Components/
Somebody came up with a pretty swell DIY fix for failing tachometers for the 90-92 range. The rest of us just get to look at a tach that's 1000's of rpms off, or just pegged. No known fix short of replacement of the tach.
It sure would be swell if one of the aftermarket manufacturers would build a really good-quality replica set of gauges for our failed OEM gauge sets. Problem is, Chevy made our third-gen gauge sets in several different flavors. That creates problems in setting up any kind of production that can be sold in volume.
Play around in the googles, and especially if you include "J-24538-A" in your search you will find links to other folks who have various Chevy products from our era, and who are experiencing the same gauge-failure issues, and without any clear fixes. There are some neat tests where you fabricate your own "tester" out of resistors, or 9v batteries, etc. But all you can learn from the tests is that the gauge aint no good.
There might be a way to remove the gauge, and disassemble the gauge, and refurbish the innards of the gauge. Can't say I've heard of it though. Reassembly of the gauge could be interesting after you've torn it apart.
I've got bad gauges (at least the speedometer works) on my '88.
Once I get several other issues of greater urgency resolved, and as much as I hate to give up the look of the OEM gauges, I'm pretty-well resigned to bite the bullet, and simply install a set of modern aftermarket gauges that at least somewhat-resemble the OEM gauge set.
This set looks pretty decent.
http://www.classicdash.com/shopping/...er-Gauges.html
You've got one those, right?
In all likelihood, the gauge itself is failing.
...which is probably better than having "nuts loose" (see diagnotic Step 6).
The correct fix would be replacement of the OEM gauge with a brand-new OEM gauge, which is currently made out of unobtainium.
Hawks will sell you used gauges.
http://www.hawksthirdgenparts.com/ca...26-Components/
Somebody came up with a pretty swell DIY fix for failing tachometers for the 90-92 range. The rest of us just get to look at a tach that's 1000's of rpms off, or just pegged. No known fix short of replacement of the tach.
It sure would be swell if one of the aftermarket manufacturers would build a really good-quality replica set of gauges for our failed OEM gauge sets. Problem is, Chevy made our third-gen gauge sets in several different flavors. That creates problems in setting up any kind of production that can be sold in volume.
Play around in the googles, and especially if you include "J-24538-A" in your search you will find links to other folks who have various Chevy products from our era, and who are experiencing the same gauge-failure issues, and without any clear fixes. There are some neat tests where you fabricate your own "tester" out of resistors, or 9v batteries, etc. But all you can learn from the tests is that the gauge aint no good.
There might be a way to remove the gauge, and disassemble the gauge, and refurbish the innards of the gauge. Can't say I've heard of it though. Reassembly of the gauge could be interesting after you've torn it apart.
I've got bad gauges (at least the speedometer works) on my '88.
Once I get several other issues of greater urgency resolved, and as much as I hate to give up the look of the OEM gauges, I'm pretty-well resigned to bite the bullet, and simply install a set of modern aftermarket gauges that at least somewhat-resemble the OEM gauge set.
This set looks pretty decent.
http://www.classicdash.com/shopping/...er-Gauges.html
Last edited by W.E.G.; Mar 9, 2013 at 12:26 PM.
Thread Starter
Junior Member
Joined: Mar 2013
Posts: 67
Likes: 0
From: Cary, NC
Car: 1986 IROC-Z/28
Engine: LB9 TPI
Transmission: 700r4
Re: Wacky fuel guage... sending unit?
Wow thanks! Lol lots of sarcasm.
And no last time I checked I dont have a J-24538-A lying around (you can tell its not for personal use because its not even named :P
And no last time I checked I dont have a J-24538-A lying around (you can tell its not for personal use because its not even named :P
Supreme Member
Joined: Jan 2006
Posts: 3,341
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Sending Information
Here’s 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 it’s range to the other.
Therefore the problem is with the sender or wiring going to it.
You can use a loose potentiometer, or you can throw together a quick little panel like this one.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If You’re Passed By Your Own Tire On The Track, It’s Time For A Pit Stop
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 it’s range to the other.
Therefore the problem is with the sender or wiring going to it.
You can use a loose potentiometer, or you can throw together a quick little panel like this one.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If You’re Passed By Your Own Tire On The Track, It’s Time For A Pit Stop
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