Need help with fuel gauge not working?

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twister360

twister360

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I recently had some work done on my 74 Duster at a local shop, as he replaced the wiper linkage bushings and installed the Schumacker pivot seal kit. Prior to this the fuel gauge worked and now it reads E and there is about 10 gallons of gas in the tank. The mechanic said he checked the wiring and all seemed in good order, and he thinks the float cracked and filled with fluid and sits at the bottom of the tank, thus the reading of E.

Your thoughts and opinions? Any way I could verify his findings, before I pull the tank and replace damaged parts?

Thanks Gary
 
Grounding strap on the tank where the rubber line runs to the tank , this may need to be cleaned , it just pops on (clips on each end to ground the sending unit) A continuity test (most volt meters has them ) if the tank is not grounded it will read E . do a search here, give me a few and I will find a thread, be right back.
 
Pretty simple, and there is tons of posts on this.

I assume you don't have a Ralleye cluster? (That is you only have a temp and fuel gauge, no oil?)

The two gauges are fed power from a regulator variously called voltage limiter, gauge regulator, IVR, etc. It plugs into the rear of the cluster.

What this means is, FIRST determine if the TEMP gauge is working. If you are not sure, use an alligator clip lead to ground the temperature sender wire. Switch the key to "run" and watch the gauge. It should quickly head on over to the "hot" reading. Don't leave the key on longer than needed, a few seconds.

If that works OK, on to the fuel gauge.

There are two ways to access the fuel sender wire. One is to remove the left kick panel and find the harness connector going to the rear harness. You need a shop manual which you can download free. You can probe the sender wire and ground it for the same test as above, or you can separate the harness and check the resistance of the sender to ground

The readings depending on fuel in the tank are variously:

L = 73.7 Ohms (empty)
M = 23.0 Ohms (1/2)
H = 10.2 Ohms (full)

The other way is to access the tank underneath, IE jack up the car. There's a connector at the sender, pulls right off. As above, you can ground the wire and check the gauge, and or you can check sender resistance.
 
Need a new brass float? Part# COAZ 9202 B at your local blue oval dealer.... If they have to order they come in packs of 2.
 
I just bought a new tank, float, filler grommet, and ground strap from Vans Auto. I see them at the Nats every year and they consistently have the lowest prices.

Anyway, the brass float looks just like my original 1964. The ground strap is powder coated black. That's nice but a ground strap with paint on it? How's that going to work? Need to clean the contact areas before installing. My sending unit seems to have good resistance so it's going back in. You can check it while it's still on the car.

Oh yeah, I think you can remove the sending unit w/o removing the tank. May depend on whether the exhaust is in the way.
 
I'm not sure how it's set up on your car. But on my 70 dart, the fuel and temp gauges have studs that stick out of the back of the cluster and have some flimsy nuts that screw onto the studs and tighten up against the circuit board. They are used to hold the gauge in place AND to complete the circuit from the circuit board to the gauge. My gauges worked intermittently even after replacing the voltage regulator. My problem ended up being that the nuts had looosened up over time and slightly corroded. I snugged them up and backed them off a few times to clean the cointact area and it's worked perfectly ever since.

Your mechanic might have wiggled them loose while he was under the dash!
 
Fault in the panel is a given in my opinion. Broken contact pin at circuit boards harness connector ? I'll lay my quarter bet there.
 
RedFish said:
Fault in the panel is a given in my opinion. Broken contact pin at circuit boards harness connector ? I'll lay my quarter bet there.
Click to expand...

if he was under there replacing pivot seals ^^^^^^^ this
 
RedFish said:
Fault in the panel is a given in my opinion. Broken contact pin at circuit boards harness connector ? I'll lay my quarter bet there.
Click to expand...

Will I have to pull the cluster the check this? This morning I've verified the ground strap in engine compartment and the jumper ground clip at the tank. I pulled and cleaned the L shaped contact on the sending unit and the ground strap. Gauge still not reading.

Thanks Gary
 
twister360 said:
Will I have to pull the cluster the check this? This morning I've verified the ground strap in engine compartment and the jumper ground clip at the tank. I pulled and cleaned the L shaped contact on the sending unit and the ground strap. Gauge still not reading.

Thanks Gary
Click to expand...

yes sir you will need to remove the inst' panel.
 
You can ohm the sending unit while in the tank to get an ohm reading to verify its working correctly or not.
 
I fixed my wife's Dart, didn't pull the dash cluster. Just did it blind. Ran a wire from the kick panel, up to the back of the gauge, then used a crimp on female blue end to plug it to the gauge post, skipping the cluster board altogether. Never took the dash out, been working for 2 years....agree with redfish, got bumped/broken pin when doing the wiper seals.
I also had to run power from the gauge next to it (not the amp gauge, one with a voltage limiting side of the gauge) to power it. Hers must have had 2 broken pins on the board, or the power side trace was burnt out.
Try the gauge wire first. You can do it with alligator clips & paper clips and a scrap piece of wire to test it.
I just did a 69 Cuda with the cluster out. Bunch of issues with the pins and plug.You can solder the posts back on, but fun putting the dash back in and not breaking them again. I had a spare broken cluster for pins. Used cut paper clips inside the pins to hold the broken pins together while I soldered them.
At that point, buy the new e-pop board. It can also be just the connections at the plug and pins, if you go in that deep. Plug holes may be stretched. They can bent made smaller with tiny screw driver. Use contact cleaner on the pins and in the plug when you put it back together
P.S. Restore the dash if you take it out, unless it's nice already. Cut the lens out, and super clean it. Then touch up the needles. You can JB weld the lens back in.
 
I rechecked the ground strap at the fuel tank and it had slipped off. I repositioned it and felt sure it would stay in place. Viola!!!! Fuel gauge now works.

Thanks for the tips. Gary
 
First and foremost I would check the voltage at the meter. I would assume that the wiring was damaged, clipped, shorted, open or any other possibility. Verify the voltage at the meter is correct and then work your way back to the tank. Check connections to the board. Are you using the original voltage limiter, now is a good time to get rid of it.
I just had the same problem with the temp gauge. First thing I did was replace the 5 vdc power supply to my meter. put it back together and works great.

If it fails all of a sudden. 99/100 times it is the source voltage. BTW, make sure the cluster is grounded properly
 
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