Fuel Guage broken ?

[darmentle]

ok so that is a factory part then that goes there. I will look around today see if i can scrounge one up. if i dont find one today i will order it.

[rich weyand]

It was the same resistor used on just about every GM car fuel gauge from 1965 though 1997.

[darmentle]

ok i have 75 Chevy here at work the only one is yard i am gonna walk out there later when i get off and  check see if that one has one.

[DnStClr]

Why don't ya just get the whole gauge?

[darmentle]

because it had had the OEM fuel gauge and then the person mounted a aftermarket fuel gauge in there to . So i dont know if that fuel gauge is bad or not . ill check it out.

[darmentle]

No luck with the resistor . i even hooked up a ground wire to the ground post on gauge and plugged it in even with a good ground still nothing. i noticed that there is one big plug going into the gauge cluster where does the ground go from there.

[rich weyand]

Well, you need the resistor anyway, because it won't work without it.  You bolted it across the back of the gauge like in the picture, yes?

The big plug goes all over the place.  What truck do you have (year, model)?  The wiring diagrams are here, but they depend on the year.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=11766.0

[darmentle]

yea i hooked it up to the correct posts

[rich weyand]

yea i hooked it up to the correct posts

Just checking.  We have people of all abilities and experiences (or lack thereof) on this forum.

[darmentle]

ok so with having dual tanks and i am only using the driver side tank passenger side is inop. My question is how does the fuel gauge know which tank to read from? The switch on the dash  i noticed the previous owner cut the wires off at the switch so you cant use the other side.

[Boone83K10]

ok so with having dual tanks and i am only using the driver side tank passenger side is inop. My question is how does the fuel gauge know which tank to read from? The switch on the dash  i noticed the previous owner cut the wires off at the switch so you cant use the other side.

no. the gauge reads it directly from the selector valve which passes the signal through from the sender. this is shown above the word "RIGHT" where the fuel tank selector valve is represented in the diagram. NOTE: In the selector valve, the components can fail separately. the "mechanical" switch can still operate and actually switch between tanks but the "electrical" signal switch can fail... and vice versa. So what I mean is that the electrical part could have failed on yours but it could possibly still be switching and the gauge won't show it.

[rich weyand]

That's correct.  The tank selector valve is actually two devices on one solenoid/motor: one mechanically selects which fuel tank fuel line (and return) to connect to the fuel pump supply line (and return), the other electrically selects which fuel tank sender wire to connect to the fuel gauge wire.

The mechanical valve can fail, not switching the fuel tank fuel line, even though the electrical switch works; the electrical switch can fail, not connecting the gauge wire to the correct sender wire, even though the fuel valve works; or the solenoid can fail (most common), so that neither the mechanical fuel tank selector valve nor the electrical fuel tank sender switch works.

[darmentle]

I don't know what the issue going on the fuel selector . He had cut the wires going to switch at the dash and said just use the driver side only. Its not big deal to me not having both tanks i just want the gauge to work. Ill probably have to get under there tomorrow and just start hooking the wires back up that he cut and see what happens. I bet that is what the issue is with the gauge is still on the inop tank.

[Boone83K10]

Technically the cut wires at the dash switch should not affect the gauge reading.

[darmentle]

so i got to work on it today some more got under the truck finally. And noticed the whole fuel valve is gone he has some 3 way device up there with the fuel lines going into it. I also found the wires to the driver side tank pulled the ground wire off it was caked in all sorts of good stuff so i cleaned it up really good and put it back together still the gauge is still doing the same thing. I also notice the wire coming threw the frame for the sending unit is a blue wire not a pink wire it goes all the way up to the junction in the fire wall.