Gas gauge experts?

[MiraclePieCo]

1950 Chevy Pickup. The oft-repeated problem: inoperative gas gauge. I checked numerous archived threads and most had bad senders or gauges. But both my sender and gauge are new.

I installed a new under bed tank with a new 0-30 ohm sender. I installed a new reproduction 12-volt gauge. There is power to the gauge. Sender has an auxiliary ground. The gauge needle sits immobile wherever it happens to be. What would be the progression of things to check?

[Donaldo]

Is the new tank grounded well ?

[47 Fasttoys]

Get a 60 or 120 ohm resister, run the signal wire to the resistor then to ground, power up the gauge, if the gauge now reads you have a gauge and sender mis-match. Some are 0-30 ohm some are 0-90 ohm and some are 90 to 270 ohm.
Rob

[tmoble]

ground the sender at the tank end, see what the gauge does. then hold it disconnected, see what the gauge does. You can also try what Rob said. I've used an inline 2 watt resistor to correct a gauge before.

If it's a new gauge it's probably an electronic version of the old gauge. I've seen several of these that were factory defect.

[joedoh]

since the sender and gauge are new you may want to check the wire between them, just run it over and under and outside of hidden as a test. if that doesnt show any result, check connections.

do you have a VOM? volt ohm meter?

1. set the VOM to continuity and put one probe on the frame and the other on the sender ground. it should beep, showing that you have a proper ground on the sender.

2. set the VOM to volts, there will be a setting for 40 and that is the one you want. put the red probe on the + terminal of the gauge and the black probe on a known chassis ground, such as a bare part of the dash. It will read battery voltage (with the key on) and this shows the gauge has the proper voltage to interpret the sender ground signal from the tank. next disconnect the S terminal and run a temp wire to ground, as tmoble said, this will make the gauge sweep.

3. set the VOM to ohms, there should be a setting that says "200" and that will be the one you want. remove the sender, test across the two terminals with the float at full drop (like an empty tank) and record the value, then record with the float at full lift (like a full tank) and record that value. They should be around your 0-30 statement. put the sender back in and read the value at whatever level the gas in your tank is at. reconnect the terminals, go to the front of the truck (still with VOM set to ohms) and test the S wire at the gauge with one probe while holding the other probe on chassis ground. it should read the same value as in the back.

if you have done all of this, verified power, ground, working gauge, working sender, good wiring, you either have either fixed or found your problem somewhere in the process, or you have the wrong gauge to work with the 0-30 ohm sender, OR you have a demon possession. in the case of the wrong gauge, resistors can help. in the case of a demon possession, strike a road flare and lay it in the driver seat.

[MiraclePieCo]

Thanks for walking me through the steps gentlemen. I'll go buy a tester and get started.

[OrrieG]

Originally Posted by joedoh

OR you have a demon possession. in the case of the wrong gauge, resistors can help. in the case of a demon possession, strike a road flare and lay it in the driver seat.

Whoa, I would find a Holy Chevrolet Priest and try and exorcism first. A little voodoo goes a long way...

[MiraclePieCo]

Sorry, but I'm far too enlightened for such superstition.

I have learned on Facebook that it's a product of chemtrails and bio-engineering by the Illuminati.

[tmoble]

nah, it's just a passing cosmic ray. they'll do it every time.

[hogfarm]

My gauge gets stuck from time to time,the float is right under filler cap.when I had bed off I tried to rotate it but the holes are not evenly spaced.Just carfull when I fill it

[mr48chev]

We now have our go to sort out the gas gauge link thanks to Joedoh in post five. Well done.

[1project2many]

in the case of a demon possession, strike a road flare and lay it in the driver seat.

Demon possession is usually cured with Mopar-ite.

[MiraclePieCo]

I "exorcised" this from the power wire to the gauge. Placed there by the previous owner. What is it, some kind of voltage reducer?

Then I ran some jumper wires to + and S, and the gauge moved to 1/4 tank. I thought I was closer to 1/2 but that'll do!

[joedoh]

yes, looks like a reducer to make a 6v gauge work on 12v. probably broken, since the gauge didnt move. check continuity on that wire you removed (one probe on each side), then if it has continuity (beeeeep) check impedance (ohms) and report back, if you dare.


I forgot to mention, with the road flare, you only need to leave it there a couple minutes, those things will burn for hours but all your problems will be exorcised in under 5.