Fuel gauge reading past full

[JamesSam]

...oh and the guage reading on the passenger tank I had to switch back to when the drivers side tank died, was totally past the full mark. I was really baffled.

 

[bwolff0820]

@JamesSam good luck on figuring it out. If you have any help it would be appreciated. Unfortunately I live in Texas and this heat is limiting me on how much I can actually work on this. Goal is to get the truck running on its own and then will tackle the massive oil leak is has. I’ve rebuilt the qjet and wasn’t too bad. Again I’ve never done anything like this before so I’m learning from here and YouTube. Just wish I could figure this one out. It’s gotta be something simple I’m missing

 

[Jgonick]

I'm going to have to let someone who knows more about the dual tanks jump in. Like I stated earlier I'm not real familiar with the selector valve. Did you ever try grounding the sender/gauge wire to see if it moves slowly to E. ? -I would do both tanks. If it doesn't then you know its not getting current.

 

[bwolff0820]

I have not tried that. I have some 14g wire I can strip and use which should work to test that. I’ll give that a try and see what happens

 

[Rumbledawg]

when my gauge went to 3 o'clock about 10 yrs ago, i had no ohm meter so i basically did everything you've done with zero results. new switching valve, new grounds, etc, etc, etc.
kept pissing in the wind hoping for a better result and getting nothing.
i figured there had to be something wrong with the sender wire (pink). my "hi-tech" solution was to start bypassing the org pink wire. started by checking the under hood plug, was ok. so i hooked a wire from the selector switch in the cab to the under hood plug- no results, next by passed the pink by hooking a wire from the plug to the selector valve. boom, had my gauge back. yes the insulation was worn off my pink leading me in the right direction, but there was also only about 3 or 4 strands of wire holding it together. just because your wire looks good, don't always mean it's good. your truck is an '83, your wiring is 40 yrs old already. they get brittle and whatnot after 40 yrs and may look fine but can be broke or damaged still inside.
same thing happened to buddy's '86 c20. first thing we did was run a wire from the plug to the selector valve- once again prob solved. hitting it 2 times out of 2 times so far with this method. my buddy was lazy though and didn't inspect his pink, he just used the bypass wire and called it a day
with dual tanks you should have this plug under the hood by the firewall near the steering column. go from here to the selector valve with a bypass wire. excuse the mud and dirt, had the truck at the river the other day...and ya, i have since bought a quality ohm meter
sometimes simple is the best

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[bwolff0820]

I’m going to try and tackle this tonight. I’ll start at the plug under the hood and go down the line like you explained. Thanks for all the input

 

[bwolff0820]

So got home this afternoon and went to work on the truck. I started with pulling the plugs on the selector valve under the truck and cleaned all the dirt off and plugged it back in. Switch now works inside the cab and have the passenger tank reading on the fuel gauge. Checked pink wire from drivers side and chased it all the way to the firewall and looks good. Going to make sure it didn’t come unplugged from the sending unit then bypass the wire and see if it reads but definitely making progress since one tank is now registering. I’ve checked the plug under the hood and the switch on the dash and everything is getting power so is has to be the pink wire coming from the sending tank. I’ll update what I find out. Still can’t get the truck to fire on its own but going to put a little more gas in the tanks as the one is only reading 1/8 tank. Didn’t want to fill it and then have to drop it again

 

[neiltee]

I'm watching this one now. I had both tanks working when I bought my truck nearly a year ago, then when one tank died on me I swear fuel went from one tank to the other because I had to switch back to the tank I wasn't using and it was full(not before I switched though!). At first I was all o er the place trying to figure out what was up thinking the selector allowed fuel to bleed from one tank in to the other... all kinds of responses and figuring out what to do next calculating the cost and time I might be able to spend on it...I am still driving around with the passenger side tank as my only tank. One day I will get my garage to diagnose maybe?

If your gas is going from one tank to the other and filling it, it probably means that the tank switching valve is not operating. The fuel return is likely to be going to the tank with the least resistance. That's to say its returning to the path of least resistance. That was the situation in my 1975 K10.

 

[JamesSam]

If your gas is going from one tank to the other and filling it, it probably means that the tank switching valve is not operating. The fuel return is likely to be going to the tank with the least resistance. That's to say its returning to the path of least resistance. That was the situation in my 1975 K10.

Thanks and cool. Useful info. Soon I will be looking in to the situation. The previous owner of my truck had both fuel pumps and the switching valve replaced before I bought my truck. Both tanks, the switch, and the valve worked properly for a few months then... the truck lost all power one day while in the driver's tank. I switched back to the passenger tank and it was filled up. I assumed it bleed o er from the tank that died. Work in progress. Thank you for your insight.

 

[vr1967]

I didn’t read all the posts, but when my gauge read at 3 o’clock, i pulled the sending unit and cleaned the connection from the float rheostat to inside pin connection at the top of the sending unit.
Got my gauge back working right.