Fuel Sending Unit

[mavtricks71]

I replaced both my Sending units "spectra" and still don't have a fuel gauge....tank grounds are very clean and tight. . I have bed off my truck would any of the grounds connected to rear lights have anything to do w it.....I sure doubt it but thought id ask.

 

[Frankenchevy]

what do you mean you don't have a fuel gauge? if you mean it isn't responsive...I'd check the function of the gauge and pop the sending units out to make sure nothing is bound up. is the gauge pegged to one side or the other?

 

[mavtricks71]

what do you mean you don't have a fuel gauge? if you mean it isn't responsive...I'd check the function of the gauge and pop the sending units out to make sure nothing is bound up. is the gauge pegged to one side or the other?

My gauge just sits on Empty, two brand new Tanks , And 2 new sending units, everything is clean and connected. I'm fairly new to these trucks....is a common issue the gauge cluster/ and or fuel gauge itself?

 

[hatzie]

Pinned at E means there's a dead short to ground somewhere between the tank ground and the gauge. It's either the wiring or the senders.

Does the gauge needle swing to 3:00 when you remove the wire from the selected sender?

 

[mavtricks71]

Pinned at E means there's a dead short to ground somewhere between the tank ground and the gauge. It's either the wiring or the senders.

Does the gauge needle swing to 3:00 when you remove the wire from the selected sender?

I actually haven't tried that....yet I might have to go in hospital today or tomorrow so now I'm not sure when ill get back to it...the joys of having Cystic Fibrosis, ill let you know when I try that out.

 

[mavtricks71]

Pinned at E means there's a dead short to ground somewhere between the tank ground and the gauge. It's either the wiring or the senders.

Does the gauge needle swing to 3:00 when you remove the wire from the selected sender?

Ok so I went ahead and tried it real quick.....my gas gauge DID go to 3' oclock when I disconnected the sending unit ....that was interesting so what could that mean?

 

[hatzie]

It means that gauge wiring to that tank is perfectly fine. The sender has a problem. It's either jammed at the bottom of the tank or the wire wound resistor element is shorted to the sender body on both ends.

Why is that?

The GM fuel gauge reads E when the sender resistance is 0Ω (a dead short to ground)
The GM fuel gauge reads F when the sender resistance is 90Ω.

When the sender is unplugged and the gauge wiring is OK the resistance can be said to be ∞.
A resistance of ∞ (an open circuit) drives the needle to the stop at the top of the gauge which happens to be roughly the 3:00 position.

Your wiring ain't shorted to ground the senders are.

 

[mavtricks71]

Welp I'm headed to hospital I do really appreciate information, hopefully I can return to my truck in 2 weeks....ill keep you post if I have any other troubles thank you.

 

[bucket]

Well I hope all goes well for you.

And I hope we can assume the tanks are not just empty.

 

[mavtricks71]

Well I hope all goes well for you.

And I hope we can assume the tanks are not just empty.

Lucky for cell phones I can still chat, I did put 5 gallons into drivers side tank, so id figure it would at least read quarter of a tank...but it was definitely below empty line on gauge.

 

[Dougnsalem]

Well I hope all goes well for you.

And I hope we can assume the tanks are not just empty.

Dang! Einstein! Lol. You don't know how many times I've forgotten to ask that. Good question.....

And hope you get better soon @mavtricks71

 

[hatzie]

Hope it's nothing too serious. In any case have yourself a speedy and un-eventful recovery.

 

[mavtricks71]

Hope it's nothing too serious. In any case have yourself a speedy and un-eventful recovery.

Thank you for concern I think I'll be fine.
Hatzie ....if I was to pull sending unit out of tank I can manually trick the fuel gauge by running the float up or down right ? And see if gauge inside truck moves?

 

[Honky Kong jr]

Thank you for concern I think I'll be fine.
Hatzie ....if I was to pull sending unit out of tank I can manually trick the fuel gauge by running the float up or down right ? And see if gauge inside truck moves?

Yes as long as you ground the sending unit.

 

[chengny]

Maybe consider eliminating the tank transfer valve as the problem first. Look under the cab - about a foot forward of the rear wall on the LH frame rail - and locate the splice point for the extension lead that runs over to the Pollak valve:

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Separate the two leads:

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and then connect common lead - the one that runs forward - to the production (LH) fuel tank sender:

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The valve (and the extension lead) will then be bypassed. Turn key to run and check gauge function. You will only read the LH tank.