First, my gas guage doesnt work. first it was all over the place, at empty then full, swinging around, untill one day it stayed at the 1/4 tank mark. Full-empty it reads 1/4 tank. I replaced the VR on the back of the cluster TWICE, once with an orig and then made my own. checked the ground, its fine. Checked the blue wire running to the sending unit, its hot when the key is on. I replaced the gas gauge, and the circut board on the back of the cluster, same 1/4 tank reading. It reads empty when the key is off, and slowley rises to the 1/4 mark with the key on. The sender for the temp gauge is missing so it doesnt work, so I have no idea if its the VR or not. Any Ideas?

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels

Any one?

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels

Maybe the gauge itself has failed?

That would be odd, since this is the second one I have put in it. Im thinking the float got stuck in the tank? How empty does the tank have to be to take the sending unit out?

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels

I'd start by checking the ground for the sender; often, the little jumper strap from the sender to the fuel line breaks or corrodes. When I've seen gas gauges quit, about 50% of the time it was the ground and 10% of the time was a sunken float, 10% of the time a loose pin on the circuit board, and the rest of the time it was the resistor assembly (especially the brush).

I'd try to empty the tank as much as possible before removing the sender, just because the sloshing weight of gas makes handling the tank much harder than an empty tank. On most models I've worked on, it was difficult to get the sender out w/o dropping the tank, but if you've got clearance, anything well under 1/2 full ought to be enough to put the level below the sender if the tank is level.

one of my friends said to check the gauge you ground the power while the gauge is disconnected and the power is on and if the needle moves to full when you ground it and back to empty after you remove it the gauge is good so you must look else where.

Your wire to the sending unit should not be "hot" it is a ground wire. take off the wire at the sending unit and touch to a good ground and then turn on the key, if the gauge is good the needle should go to FULL. make sure you have it grounded good though. If this happens your sending unit is bad. Try to get out as much fuel as possible but I have found in the past that I still spill fuel so make sure you have something ready to catch the gas with.

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64 barracuda
64 valiant convertable
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74 vw beetle convertable
79 E-250 4WD van
94 dodge dakota

that makes more sense because i have the problem where it only indicates 1/4 and moves back and forth from empty to 1/4

I had a similar problem. Wiring is a mess, but one day filled tank and guage stopped working.

When I put the key in, the fuel guage would go up a bit to E, so figured the guage was working and I found this article and followed it after determining that the sending unit wasnt the issuel. it was the ElectroMechanical Regulator. I went out and bought a soldering iron, the regulator and a capacitor, followed directions and it works now, I did however short the dash lights in the process ;(

If your dash looks like this in the pics then you can try it, good luck. it was actually pretty simple, my first time using a solder iron.
http://www.allpar.com/history/mopar/electrical2.html

I didnt do the heat sink mounted to the board, mine is sticking out with electrical tape around the regulator, hopefully it wont overheat.

You really should put a heat sink on it. The regulator works by converting that extra 7 volts into heat. If there isn't a good way to get rid of that heat, the regulator could burn and short out.
That would mean you have full battery voltage going to the gauges. If that happens, your gauges will burn up in a few seconds.

When my original mechanical regulator failed, the contacts happened to be closed. That sent the 12v to the gas and temp gauges. By the time I realized there was a problem, they were already fried.

I had to buy two complete instrument clusters to get two working gauges. And on top of that, now my gas, temp and amp gauges are all different: grey, yellow and white.

My gauge works until just above 1/4 full. Then it stays there until I fill up again. I plan on pulling the sending unit from the tank and looking at the contacts on the float. dusterguy225, did you figure out your problem, and did you end up pulling the float assembly?

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63 Dart GT Convertible

I pulled out the sending unit yesterday, and some how it was cocked off to the side. You can see that the pickup arm is about 25 degrees off to the left, and the float arm was about 5 degrees to the left. This also twisted the housing where the contact is, so that's what probably caused the problem. The replacement unit went right in, and now the gauge works perfectly! Full reads past the F, but at empty (like when I first installed it), it is just at the line before E.

What's really weird is that I believe that this is the first time the unit has been removed, because I had to chip away all the underbody coating to get to the thing. The entire underbody is covered with this stuff, and it was easily a quarter-inch thick on the swivel ring, even on the wire and gas line. Could this have been installed this way from the factory?

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63 Dart GT Convertible

Can u post a full pic of that Gauge set up please

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68 225 Dart "life under the hood, is the life for me" -By Me