Author Topic: Fuel Gauge Not Working  (Read 15266 times)

Offline birddog615

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Fuel Gauge Not Working
« on: January 09, 2012, 05:28:04 PM »
Hey y'all. This is my first post and I'm hoping I can get some answers. I bought a '79 K10 Silverado three months ago and the fuel gauge is not working. The gauge cluster is the one with the tach, so the fuel gauge is small. I have removed the bezel and pulled the gauge out, but don't know how to test the clips (3 of them) to tell if juice is reaching the gauge, or if the gauge is bad. If I missed some important info you need to help, I'm sorry. Let me know what info you'll need and I will get it posted. Thanks!
1979 K10    2004.5 Dodge Ram 2500 4x4    2006 Chrysler 300C SRT8    1975 Harley Davidson Ironhead

Offline pendergraft2111

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Re: Fuel Gauge Not Working
« Reply #1 on: January 09, 2012, 05:41:21 PM »
I think the problem is more likely at the tank... If I remember right you can pull the harness at the tank and ground the side from the tank. If the gauge moves then its not the gauge... I'm new here too but I am sure someone else will chime in if I am wrong.
When life gives you lemons... find someone who wants lemons, sell them and buy what you want.

Offline birddog615

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Re: Fuel Gauge Not Working
« Reply #2 on: January 10, 2012, 06:54:20 AM »
Okay, thanks I'll give that a whirl.
1979 K10    2004.5 Dodge Ram 2500 4x4    2006 Chrysler 300C SRT8    1975 Harley Davidson Ironhead

Offline bake74

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Re: Fuel Gauge Not Working
« Reply #3 on: January 10, 2012, 07:59:40 AM »
I think the problem is more likely at the tank... If I remember right you can pull the harness at the tank and ground the side from the tank. If the gauge moves then its not the gauge... I'm new here too but I am sure someone else will chime in if I am wrong.

     pendergraft is on the right track, most fuel gage problems start with the ground on the fuel tank either going bad, or getting rusty or corrided.  Clean and re-attach the ground and make sure it is making good contact and report back your findings.
     Then we can go from there about trouble shooting the actuall gage.
#1: The easiest and most obvious solution to any problem is 99% of the time correct.
#2: There is no such thing as impossible, it just takes longer.
  74 k10, 77k10    Tom

Offline birddog615

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Re: Fuel Gauge Not Working
« Reply #4 on: January 10, 2012, 04:49:20 PM »
Will do! Thanks guys.
1979 K10    2004.5 Dodge Ram 2500 4x4    2006 Chrysler 300C SRT8    1975 Harley Davidson Ironhead


Offline birddog615

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Re: Fuel Gauge Not Working
« Reply #6 on: January 14, 2012, 01:19:55 PM »
Okay, got up under the truck today and found that both tanks ground in only one location, the left side. The wire was purple which I noticed from the schematic is the proper color. I removed the ground and cleaned the connector and roughed up the frame with a wire brush and reconnected...no luck. My factory oil pressure gauge and temp gauge do not work either (I don't know if they are all connected together somewhere or not). So what's my next course of action?
1979 K10    2004.5 Dodge Ram 2500 4x4    2006 Chrysler 300C SRT8    1975 Harley Davidson Ironhead

Offline zieg85

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Re: Fuel Gauge Not Working
« Reply #7 on: January 14, 2012, 01:24:03 PM »
Check to make sure your plug is all the way in to the back of your instrument cluster would be what I would check next.
1985 C10 Custom Deluxe 4.1L 3 on the tree
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 4.56 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 Custom Deluxe 5.7L 3 on the tree 2.73

Offline birddog615

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Re: Fuel Gauge Not Working
« Reply #8 on: January 14, 2012, 01:30:49 PM »
Is there a plug? I thought the printed circuit board connected to the 3 prongs on the white plastic mounting panel.
1979 K10    2004.5 Dodge Ram 2500 4x4    2006 Chrysler 300C SRT8    1975 Harley Davidson Ironhead

Offline zieg85

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Re: Fuel Gauge Not Working
« Reply #9 on: January 14, 2012, 02:16:45 PM »
There is a plug that carries all the wires to operate your instrument cluster except the mechanical speedometer.  I have had trucks that for whatever reason was only plugged in partway only catching some of the circuits.  If it is plugged all the way in check the printed circuit board for bad spots.  I found this site when I was researching a gas gauge issue over 2700 posts ago.  Mine ended up a bad circuit board.  My gas gauge would work except when I pulled on the lights.  If I dimmed the dash lights all the way to off the gauge worked.  I couldn't see anything wrong with it but I bought a used one from the pick and pull and that was it.  I then put back in to the used cluster all my gauges and speedometer and the used one came with a clock...
« Last Edit: January 14, 2012, 03:03:01 PM by zieg85 »
1985 C10 Custom Deluxe 4.1L 3 on the tree
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 4.56 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 Custom Deluxe 5.7L 3 on the tree 2.73

Offline bd

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Re: Fuel Gauge Not Working
« Reply #10 on: January 14, 2012, 02:43:23 PM »
There is a plug that carries all the wires to operate your instrument cluster except the mechanical speedometer.  I have had trucks that for whatever reason was only plugged in partway only catching some of the circuits.  If it is plugged all the way in check the printed circuit board for bad spots.  I found this site when I was researching a gas gauge issue over 2700 posts ago.  Mine ended up a bad circuit board.  My gas gauge would work except when I pulled on the lights.  If I dimmed the dash lights all the way to off the gauge worked.  I could see anything wrong with it but I bought a used one from the pick and pull and that was it.  I then put back in to the used cluster all my gauges and speedometer and the used one came with a clock...

Zieg, you beat me to it! 

Birddog, sounds like you either lost ignition or ground to the cluster.  If you still have issues with your gauges after checking the above, with the ignition switch turned ON, check both sides of your fuses using a test light. 

GM uses pink w/ black stripe wiring for ignition and solid black wiring for ground in the dash harness.  If necessary, you can probe the harness cluster plug for power and ground.  If the pink ignition wire(s) aren't energized with the key ON, your gauges won't work.  The black ground wire may be attached to the cab sheetmetal by a screw, a spade terminal, or a u-clip; in any case make sure there is a good connection to clean bare metal.

Referring now to the printed circuit on the back of the cluster, even light oxidation of the copper foil wherever there is a mechanical connection (like at the harness plug or the steel spring clips at the back of the gauges) can cause connection problems.  You can clean the connections, but be careful that the foil doesn't peel loose from the flexible plastic "board."  The board is fairly durable, but doesn't like to be bent excessively.

Hope at least some of this helps.   :D

Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline birddog615

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Re: Fuel Gauge Not Working
« Reply #11 on: January 16, 2012, 07:20:21 AM »
All right! I'll check those areas! Its funny cause out of the four small gauges, only the volt gauge works. Thanks guys.
1979 K10    2004.5 Dodge Ram 2500 4x4    2006 Chrysler 300C SRT8    1975 Harley Davidson Ironhead

Offline birddog615

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Re: Fuel Gauge Not Working
« Reply #12 on: January 28, 2012, 03:17:15 PM »
GOT IT WORKING!!!
I pulled the gauge this morning and check the clips with a volt meter. I used the prong that is supposed to be the ground to check the ignition hot. It showed 12V. So I knew all the connections behind the dash were good and the ground was good. Next I checked the prong for the sending unit...nothing. So I went back under the truck and started poking around. I found a wire with black tape and investigated further. The two wires were connected with a butt connector, but the wires slid out pretty easily, so I used a new connector with the shrink wrap at both ends. Got it all fixed up, reconnected the battery, and checked it out. Both fuel tanks are registering. Thanks guys for all your help! Now I got to get the stock temp and oil pressure gauges going (someone switched them to the Sunpro under the dash ones).

Thomas
1979 K10    2004.5 Dodge Ram 2500 4x4    2006 Chrysler 300C SRT8    1975 Harley Davidson Ironhead

Offline birddog615

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Re: Fuel Gauge Not Working
« Reply #13 on: January 28, 2012, 04:40:17 PM »
Just noticed...is the gauge supposed to read all the time? Even with the key out, the gauge reads what the tank has in it.
1979 K10    2004.5 Dodge Ram 2500 4x4    2006 Chrysler 300C SRT8    1975 Harley Davidson Ironhead

Offline zieg85

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Re: Fuel Gauge Not Working
« Reply #14 on: January 28, 2012, 05:03:31 PM »
Just noticed...is the gauge supposed to read all the time? Even with the key out, the gauge reads what the tank has in it.

yes and no.  Yes it stays when you shut the key off but if drained, siphoned or a leak occurs the gauge won't compensate until you turn the key back on.
1985 C10 Custom Deluxe 4.1L 3 on the tree
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 4.56 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 Custom Deluxe 5.7L 3 on the tree 2.73

 


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