Gas gauge issues

[INSIDIOUS '86]

My gas gauge isn't reading anything and the needle limp. I have two good verified gas gauges my printed circuit board is good and my switch was working fine last week. All I did was change my mechanical oil press and water temp gauges to sunpro and drive it for a week with no gauges. I don't know what the hell is going on but with the way this thing eats gas I NEED my fuel gauge working
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It's an 86 with duel tanks if that helps

[Gigem]

bad ground?

[hyatt]

remove sender wire at tank Guage should go past full Ground sender wire guage should go past empty If not guage or wire to guage bad

[spencer_41188]

anyone have the wire diagram for the dual tanks my 88 was efi but the guy i got it from changed it over to carb it would be nice to get both tanks working and the gauge reading

[INSIDIOUS '86]

I pulled the gauge and have two other good gas gauges that I jumped directly to the harnes plug and still no gauge movement or anything and I doubt that both sending units in both tanks went completely bad at the same time. I can flip the switch and hear the diverter valve working so the switch still has to be good idk what else it can possibly be
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[hatzie]

Originally Posted by spencer_41188

anyone have the wire diagram for the dual tanks my 88 was efi but the guy i got it from changed it over to carb it would be nice to get both tanks working and the gauge reading

See my signature...

[1981Stepside]

When you say you jumped them directly to the harness plug, do you mean the harness into the instrument cluster or the harness on the diverter valve? If you mean the instrument cluster, you might have a break in the wire between the fuel tank and instrument cluster. Trace the wire from the fuel tank to Tue selector valve and jump it there, and work your way forward.
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[88Jimmy4x4]

when you painted the skull on it you killed it lol

[hatzie]

Originally Posted by INSIDIOUS '86

I pulled the gauge and have two other good gas gauges that I jumped directly to the harnes plug and still no gauge movement or anything and I doubt that both sending units in both tanks went completely bad at the same time. I can flip the switch and hear the diverter valve working so the switch still has to be good idk what else it can possibly be
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I assume you checked the ground and power harness splices behind the instrument panel.

In 86 the valve picked which sender feeds the gauge. At the valve plug the solid pink wire is the gauge feed and the pink wires with stripes are the senders.

Unplug the valve and switch the ignition on. If this nails the gauge at 3:00 then the pink wire is OK.

Bypass the valve sender switch as a test.
Jumper the Right Hand sender wire, Pink with Black stripe, to the Solid Pink wire using a jumper wire and the proper mating gender weatherpack pins. Check the gauge with the ignition on. Repeat for the Left Hand Sender wire.
If this works the switch inside the valve has gone bad. If not you narrowed it down to one or both sender wires.

[hyatt]

If wire was broken between guage and tank it would read past full Remove the dash guage and with a test light and key on 1 terminal should check hot Then clip the test light to a hot termimal and touch the other 2 terminals 1 should light the light bright It will be the ground Touch the third and it will probally light dimmer or slight pulsate where sender is reading ground resistance It sounds like you have either no 12v or no ground at the guage

[motornut]

Yes,
sender off
should be over full
grounded would be E
if no movement,I'd confirm the power and ground to gauge are good
sounds like a good time to bypass it and have a manual choice of which tank to read
good for those Earnhardt pit stops lol

[88Jimmy4x4]

did it work before you took apart and painted on it?

[INSIDIOUS '86]

Yah it all worked fine before everything pulled apart. All I changed was the gauge face and the Equuis gauges with sunpro and then added a clock.
When everything is plugged in the needle is limp like there is no power if I hit the switch to swap tanks nothing happens but you can hear the diverter valve work and it was working last week. Hatzie I looked earlier in your sig and didnt find much for wiring stuff since my iPhone wont show it all
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[hyatt]

check your printed circuit at the back of the guages at the silver snap in clips You are not getting 12v or ground also check your guage fuze

[INSIDIOUS '86]

I'm getting gauge lights but is there a diff fuze for gauges? I checked circuit board for continuity and it checked out. But I'm not getting 12v off the fuel system wiring from the clip that goes to the gauge bezel
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[hatzie]

Originally Posted by INSIDIOUS '86

Yah it all worked fine before everything pulled apart. All I changed was the gauge face and the Equuis gauges with sunpro and then added a clock.
When everything is plugged in the needle is limp like there is no power if I hit the switch to swap tanks nothing happens but you can hear the diverter valve work and it was working last week. Hatzie I looked earlier in your sig and didnt find much for wiring stuff since my iPhone wont show it all
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Try this.
ST_352_86_1986_Chevrolet_GMC_Light_Truck_Wiring_Manual_CK_10_30_Only.pdf

[hyatt]

yes there is a guage fuze

[INSIDIOUS '86]

Yah the fuze keeps blowing idk why
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[hyatt]

Originally Posted by INSIDIOUS '86

Yah the fuze keeps blowing idk why
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First thing Unplug the big plug from cluster and replace fuze If it blows you have wiring problems in main harness If not short is in cluster I would check is where you installed the aftermarket guages in the panel Check and see if they are shorting against the origional printed curcuit

[hyatt]

I noticed you had a factory tach If you added that to your cluster without changin to matching printed curcuit you will have all kinds of problems

[INSIDIOUS '86]

It's fixed there was a wire rubbed raw and shorting and blowing the fuze.
Hatzie the diagram was helpfull thanks for the help guys Ile get pics up when it's all together
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[INSIDIOUS '86]

Finished product
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