fuel guage issue

[86chevyk20]

hey guys gota question.

the cab that i put on my k20 (old one was rotter) had a selector switch for dual tanks. the cab didnt come with the switch.

I have a new tank, new unit in tank, new wires and when i start my truck the guage goes about 1/4 inch past full. when i pull the power wire off its drops to E. but iv drivin 50 miles and the guage didnt move so where should i start? could the switch not being there be an issue? other advie?? driving me nuts

 

[FRANKENTRUCK]

I would check the ground wire. If that is not it I would see if the sending unit is compatable with your gas tank.

 

[Beatdown Z]

Where's this ground wire you speak of located?

 

[afraziaaaa]

If the gauge pegs to full with they key on, you most likely have your gauge hooked up to the trucks charging system (battery) instead of the sending unit. If you have a wiring diagram I would start there and make sure the connections are correct.

I am pretty new to these trucks, so this is just a lead for you to follow, but I do work on robots for a living so when it comes to electrical circuits I like to think my opinion is credible at least!

Good luck.

 

[robert8096]

Where's this ground wire you speak of located?

It is located externally on the sending unit in the tank. It runs from the top of the sending unit to a bolt on the frame. Most of the time when the gauge pegs it is one of three things. Bad sending unit ground, broken wire between the sending unit and gauge or bad sending unit.

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[robert8096]

hey guys gota question.

the cab that i put on my k20 (old one was rotter) had a selector switch for dual tanks. the cab didnt come with the switch.

I have a new tank, new unit in tank, new wires and when i start my truck the guage goes about 1/4 inch past full. when i pull the power wire off its drops to E. but iv drivin 50 miles and the guage didnt move so where should i start? could the switch not being there be an issue? other advie?? driving me nuts

Remove the gas gauge from the cluster. There are three connections for the gauge. One is ground ( for the cluster) One is +12 for the gauge and the last is the wire from the sending unit. Get a digital multimeter and check the OHM value of the wire that feeds the gauge from sending unit. It should read 90 +/- ohms when the tank is full then 0 +/- empty. Place the ground probe of the meter to a good ground and the positive probe to the feeder wire and see what you get in OHMS. It is best to have the sending unit out of the tank and grounded via the ground wire on the sending unit. Move the float up and down and the ohm value should change between 0-90 ohms. If this is working then check to see if you have a good ground at the ground connection to the gauge in the cluster also check to see if you have 12v at the other connection for the gauge when the key is on. I have seen the contacts where the gauge press into the cluster become corroded or break causing weird problems.

What you are describing is opposite of what should be going on. If you pull the feeder wire off the sending unit with the gauge under power it should go to the right . Are you using the wiring harness that is original to the dual tank cab? If you are not running dual tanks then you need to trace the feeder wire back and eliminate the dual tank switch. You should have a continuous wire run from the sending unit to the gauge cluster.

Happy hunting.