OK I'm stumped..

[Stepsideride]

Ok I have an 84 2 wheel drive SWB Stepside that has been giving me hell with the fuel gauge not working... I have looked at every manual I have and and Ive seen two different wire schematics which is leaving me dumbfounded as to whats going on...I took the time to take out the cluster to inspect the printed circuit and all is well on it but I happened to notice that this cluster is out of a 4 wheel drive because light was showing through the light bulb holder hole and I saw the words 4 WHEEL DRIVE.....So can anyone on here help me figure this freaking issue out???


Keith?? anyone?

[clinebarger]

The dual tank option is the reason for two different wiring diagrams. So what is the gauge doing? reading empty? reading way past full?

[Stepsideride]

below empty at the moment....my truck only has a single tank though.

[clinebarger]

Unplug the sender wire at the tank (pink wire). If the gauge pegs past full the float has most likley filled with fuel & has sunk to the bottem of the tank. If it stays at empty the sendor wire is shorted to ground, or the gauge is bad , or there no power at the gauge.

[Stepsideride]

See thats what makes me think the cluster isnt compatible with the truck...brand new sender and brand new gauge

[clinebarger]

Im thinking the wire between the gauge and sendor is shorted to ground. Is the printed curcuit board it good shape where the plug goes? It does not make a differance if the cluster is from a 4x4.

[Stepsideride]

Yeah the printed circuit seems to be Fine.....I had my multimeter out tryin to see if I had continuity from the sender to the gauge though the wire that showed continuity was not at the pin I traced to the fuel gauge get what Im saying.

[clinebarger]

Are you sure your testing the correct pin? power will be pink&black the sendor wire will be pink.

If the wire is broken somewhere it will not show continuity. But the sendor hook up on the gauge is getting grounded some how.

[Stepsideride]

I found the problem....melted wires just above the fuse panel....looks like a wire harness is in order.

[clinebarger]

The harness can be repaired, If wires are melted you need to find the source of the short/bad ground/component drawing to many amps.

[Stepsideride]

Thats what my uncle was just telling me....he has an 87 that I am going to get the harness from..and as far as the melted wire cause I found that problem already the wiper motor ran slow as **** even on high.

[kris's66lwb]

hey sorry to thread jack but i have a similar problem its a 1980 c10 lwb dual tankes only feeds from the right tank and the guage on the left tank read way past full im thinking int the realy does anyone have a schematic for this set up

[78-5.3]

i have the same problem but not melted wires !!! my gauge in the truck reads empty but i discontected the PINK wire in the engine bay HOOKED it to another fuel gauge and got 12v and GROUND directly from the battery and THAT GAUGE READS over full , so maybe i thought it was the test gauge i was using and tried it again and again it read over full with the second gauge ??? what is going on with mine ????

[clinebarger]

Originally Posted by kris's66lwb

hey sorry to thread jack but i have a similar problem its a 1980 c10 lwb dual tankes only feeds from the right tank and the guage on the left tank read way past full im thinking int the realy does anyone have a schematic for this set up

Here you go, I got two, there for a 82 but should be real close.

[clinebarger]

Originally Posted by 78-5.3

i have the same problem but not melted wires !!! my gauge in the truck reads empty but i discontected the PINK wire in the engine bay HOOKED it to another fuel gauge and got 12v and GROUND directly from the battery and THAT GAUGE READS over full , so maybe i thought it was the test gauge i was using and tried it again and again it read over full with the second gauge ??? what is going on with mine ????

Are you sure your on the right pink wire? do the test in post #4 and get back to me. Doing it at the tank ensures that you have the right curcuit.

[78-5.3]

yup got the right pink wire goes from the engine bay to the connector at the gas tank i disconnected the connector and got another battery i connected the battery 12v+ to the left hand stud then the GROUND to the bottom middle stud then the gauge wire that goes to the tank to the right hand stud on a spare gauge (i had 3 ) soon as i put the 12v and ground on the studs the gas gauge went straight to full, and after attaching the gauge wire had no affect on all 3 spare gauges

[clinebarger]

Originally Posted by 78-5.3

yup got the right pink wire goes from the engine bay to the connector at the gas tank i disconnected the connector and got another battery i connected the battery 12v+ to the left hand stud then the GROUND to the bottom middle stud then the gauge wire that goes to the tank to the right hand stud on a spare gauge (i had 3 ) soon as i put the 12v and ground on the studs the gas gauge went straight to full, and after attaching the gauge wire had no affect on all 3 spare gauges

When you say "got another battery" Your not using the battery in the truck?
Try grounding the other battery to the truck see what happens.

When you had the harness disconnected did you see what the gauge in the truck did with the key on?

The gauge pegged past full means theres a open curcuit in the sender wire, sender, or the sender is not grounded.

[78-5.3]

Originally Posted by clinebarger

When you say "got another battery" Your not using the battery in the truck?
Try grounding the other battery to the truck see what happens.

When you had the harness disconnected did you see what the gauge in the truck did with the key on?

The gauge pegged past full means theres a open curcuit in the sender wire, sender, or the sender is not grounded.

i didnt ground the the battery to the truck im thniking there something wrong with the sender in the tank maybe because the gauge in the truck reads empty and the spare gauges read over full if i disconnect the wire the gauge pops ups to 1/4 ????

[clinebarger]

Originally Posted by 78-5.3

i didnt ground the the battery to the truck im thniking there something wrong with the sender in the tank maybe because the gauge in the truck reads empty and the spare gauges read over full if i disconnect the wire the gauge pops ups to 1/4 ????

The battery has to be grounded to the truck to complete the curcuit. Your probably right about the problem being inside the tank. Float full of fuel?

But to be sure, unplug the sender and your existing gauge should go past full.
This will tell us the gauge is OK and the curcuit is not shorted to ground.

[clinebarger]

On a side note. Im guessing your running a inline pump? Now whould be a good time for a 87 model tank & sender with a high pressure pump in the tank.

[78-5.3]

im running a 87 sending unit with the hi psi corvette pump for my LSX i have the two wire from a 87 running from the connector at the tank up to the front, 1 wire i think its grey goes to the relay for my fuel pump the other goes to my gauge ,remember i pulled this off another 87 truck to put in my 78 ,so its got a connector in the engine bay

but you telling me to get under the truck disconnect the connector at the tank and see if it pegs out right?

[Stepsideride]

thats what hes saying.

[78-5.3]

Originally Posted by Stepsideride

thats what hes saying.

thanks for the confirmation Stepsideride

[clinebarger]

[QUOTE=78-5.3 but you telling me to get under the truck disconnect the connector at the tank and see if it pegs out right?[/QUOTE]


Yes. This helps narrow down where problem is.

[kris's66lwb]

thanks tons cline but one question is the fuel tank slector and meeter valve under the bed with the lines connected to it?