fuel gauge/ sending unit/ pump problems?

[txchainsawgogi]

So my gauge is jumpy and innacurate, and my tank selector switch doesn't work. Can i get rid of the switch and just have one tank selected(drivers side)? I'd also like to ditch the passenger tank since its gunky and not worth flushing out.

[txchainsawgogi]

Also, assuming the gauge isn't bad...how do I get it to display an accurate reading? Replace the fuel sending unit?

[87454westernhauler]

i bet that it needs a new sending unit for the gage problem. i have been having kind of the same problem with my 87 selector valve too, i think the valve is bad, don't even have the pasenger tank any more anyways. i am curiose too on how to by pass the valve for wiring.

[ccz145a]

jumpy readings are usually the sending unit reostat (varaible resistor) getting rusty. replace.

[txchainsawgogi]

Where is the reostat located?

[Bodyswap]

It is easy.  You run 1 line, or set of lines if you have a return, from the fuel pump to the tank that you want.  This bypasses the selector all together.  Then all you have to do is unhook the switch in the cab and get rid of the parts if you don't think you might want to hook them back up later.  Make sure that you don't leave any hot wires loose when you unhook the switch cause this could be a problem in the future.

[Grim 82]

Where is the reostat located?

It's in the tank

[txchainsawgogi]

Ok. Doesn't sound too bad. Here's the thing though... neither tank displays correct readouts. Would the reostat be bad in both tanks or is there a more likely problem?

[Bodyswap]

It is hard to tell.  I would test your gauge with a multimeter to see what the output is at full and empty.  If that reads ok then I would assume that it is the gauge.  You can probably find one cheap if you have a pull your own style salvage yard. The sending unit is cheap at oreilly's or anywhere for that matter.  I can't say for sure what a gauge would cost since I have never replaced one with a factory one.  It is a good excuse to go get a cool set of aftermarket gauges and put them in.

[txchainsawgogi]

I've got a multimeter and I've had the gauges off before so no problem there. What readout number should I be looking for? Low resistance to none or what?

[ccz145a]

90 ohms is empty, 0 ohms is full. Or is it the other way around? Easy enough to find out if you are testing.

[txchainsawgogi]

So pull the gauge and test the back of it with a multimeter? I'm also gonna check the board, and reostat. Just do away with the other tank/tank selector.

[ccz145a]

reostat is on the sender. hard to test the reostat without tank dropped, but I think that's where your problem is. To test the guage, you'll need to find a known good sender or replicate the resistor some other way.

[txchainsawgogi]

I guess ill just go straight to the reostat then. Unstrap the tank/ cap off the lines and then what?

[Grim 82]

If the straps are rusty and in danger of being destroyed if you mess with them, leave them on the tank and remove the hangers from the frame instead. When you drop it down and disconnect the lines and wire for the sending unit, take a pick and compressed air if you have it to clean up the top, and use a hammer and punch/chisel to turn the retainer off the top. Then the sending unit will come out in one piece. Hopefully your tank isn't that full