Fuel Gage Slightly Past Full

[44SAA]

I have spent a lot of time chasing wires and finally have 2 functioning fuel tanks. I have read a lot about open circuits causing gauges to peg at 3:00. In fact, at one point during my repair when i disconnected the fuel selector switch on the dash- it did peg 3:00. I have just topped off both tanks and while they aren’t pegged at 3:00, both tanks are showing about 1/4 past full. Is this a common occurrence? 1980 C20

[Factory Guy]

I think you may have a Fuel sending unit/ground issue. I had a similar problem on my 70 Chevelle. I replaced my Fuel sending unit and re-grounded it and solved it.

[Bandit130]

X2 on the sending unit. Mine pegged at 3:00 until it was replaced then worked correctly.


FYI. If you put your truck info in your signature, year, model, engine trans. etc. You won't need to put it in your posts each time.

[44SAA]

Sending unit...not what I wanted to hear

[WorkinLonghorn]

Mine is about 1/8 past full when topped up and I never thought twice about it. As long as the empty reading is accurate it's ok by me. 1/4 past might be too much though. I'd have to see it. Is your empty reading correct? On mine, when it shows empty, I still have about 2 gallons left and the pointer will go a little past the mark at true empty. If the empty reading is too high then you just need to bend the float rod a little, but I assume you already know this. -BA

Ok sure, if both tanks do that it's prob. not the sender. I guess I didn't read the post.

[44SAA]

Pic of gauge, both tanks topped off.

[Dead Parrot]

If it does the same thing on both tanks, probably not sending units. Thinking it would be unlikely two senders would fail the same way and the same amount.

Could be corrosion in the switch.

Might be worth while to also check for corrosion on the gauge cluster contacts and the resistor behind the gauge.

Does yours have the one wire solenoid valve or the several wire motorized version?

[44SAA]

Good thought Parrot- I have the one wire solenoid switch

[akart]

Man,I wouldn't touch a thing.You have two working tanks.run them till they are out of gas and switch over to the other and repeat and see where you're at. Or maybe you want to crawl under there and start dropping tanks and buying 125.00 sending units or maybe remove the bed,that would be fun too but easier access. My tanks on 6 Chevy trucks all showed high when full and had some left when on empty. If it ain't broke don't fix it !!!! Unless of coarse you want to open up a can of worms and spend a lot of time and money,have your truck down for a while and maybe not fix anything. Just run it.

[Dead Parrot]

On one wire setups, the switch has the wiring and contacts to switch between the senders. IIRC - on the motorized version, the valve contains those parts.

If yours has the 6 port solenoid, last I heard, those were un-obtainium. 3 port variants are still available. Something to consider if you decide to start swapping tank parts. If you have a 6 port and break it, the scope of your repair just got more complex.

I am with akart. If the gauge does a full sweep for both tanks and just reads high, put it in the quirk department and drive it. The next time you have the gauge cluster apart would be a good time to check and clean all the fuel gauge contacts.

[44SAA]

Akart- you’re right, I’m keeping it as is.

Parrot- the 6 ports are indeed very tough to find, borderline impossible. However, if you can believe it I randomly found one off Amazon of all places about a yr ago for about $50. Some mechanic in CA put one up for sale. I asked if he had more, and he didn’t. I also found one at the yard, fought the copperheads and chiggers the whole way. I bench tested it and it works. So, I do have one spare. Thanks for the help fellas

[akart]

Originally Posted by Dead Parrot

On one wire setups, the switch has the wiring and contacts to switch between the senders. IIRC - on the motorized version, the valve contains those parts.

If yours has the 6 port solenoid, last I heard, those were un-obtainium. 3 port variants are still available. Something to consider if you decide to start swapping tank parts. If you have a 6 port and break it, the scope of your repair just got more complex.

I am with akart. If the gauge does a full sweep for both tanks and just reads high, put it in the quirk department and drive it. The next time you have the gauge cluster apart would be a good time to check and clean all the fuel gauge contacts.

Do you want a 6 port valve? Google ACDelco U7001. Lots of vendor have them Aoto Zone,Rock Auto.Summit ........ Then down load the install schematic from Hazzie if that's what you want to do. Good to have a spare. And good on you to leave it alone !!!

[Dleslie212]

Originally Posted by Dead Parrot

On one wire setups, the switch has the wiring and contacts to switch between the senders. IIRC - on the motorized version, the valve contains those parts.

If yours has the 6 port solenoid, last I heard, those were un-obtainium. 3 port variants are still available. Something to consider if you decide to start swapping tank parts. If you have a 6 port and break it, the scope of your repair just got more complex.

I am with akart. If the gauge does a full sweep for both tanks and just reads high, put it in the quirk department and drive it. The next time you have the gauge cluster apart would be a good time to check and clean all the fuel gauge contacts.

This is exactly what I did... I broke my six port trying to replace some fuel hose. Ended up having to replace with the new style, run all new wiring to it, and wire in a whole new switch