New voltage regulator. Retain capacitor?

[Dino]

The sender wire goes straight to the fuel gauge so when you ground the wire the gauge will read full.  That part is normal.

So your gauge does nothing when you have the sender hooked up to the fuel gauge wire and ground?

94 is way high as well, but don't focus too much on the numbers.  When I calibrated my fuel gauge I did it with the sender out of the car.  I calculated the midpoint of the float arm travel and set the gauge to read half.  I then tweaked to have it read just passed full with a full tank.  A reading of a quarter full means I have about 5 gallons left.

Do it this way and your gauge will be properly calibrated for your sending unit.

[K9COP]

Yes both battery cables were connected at the time I tested the sender. I was a cop too so dick away all you want, I can take it.

Nice job brother!

I'm a little confused but I think you're saying that with the correct connections (ground on sender to battery -ve and 'signal' on sender to gauge) you get nothing, but with 'signal' wire that would be on the sender connected to ground at the sender end, you get a 'full tank'.

My interpretation from that is a break in your temporary ground wire. Have you tried straight to the frame for the sender unit ground terminal?

Stay safe,

K9

[Pete in NH]

Hi 69DC and welcome to the group.

I just saw this thread and the issue you are having with your fuel gauge. In a Chrysler gauge system 10 ohms at the sender = full, 24 ohms = mid scale and 73 ohms = low or empty. All gauges and senders use these numbers, fuel, oil pressure and temperature gauges.

Your new fuel tank sender will be a bit off with 94 ohms but almost all these reproduction senders are not quite on specification. From your description and measurements it seems the sending unit is working and you have an open ground path. Many Chrysler products have a metal  strap that bridges the rubber fuel line from the tank to the metal 5/16" fuel line to provide a ground to the sending unit. The gauge will not work without this ground. You can use your ohm meter to check and make sure the sending unit is grounded when installed in the tank. Also, be careful grounding the sending wire to the fuel gauge, you can damage the gauge.

[69dc]

Thanks for the input Pete. When I run a separate new ground wire from the battery to the sending unit it should eliminate an open ground as the problem shouldn't it? It looks to me like I am completing a circuit by plugging the sender wire into the sending unit and grounding it to the battery?

[Pete in NH]

Thanks for the input Pete. When I run a separate new ground wire from the battery to the sending unit it should eliminate an open ground as the problem shouldn't it? It looks to me like I am completing a circuit by plugging the sender wire into the sending unit and grounding it to the battery?
[/quot


Yes, with that separate ground wire back to the battery you should have completed the circuit. Yet, as I understand it the gauge still doesn't work. If the sender is installed in the tank it still may not be grounded by grounding the tank itself. The rubber gasket may be isolating the sender from the tank electrically, even though you would think the lock ring would connect it. That is why Chrysler used the grounding strap between the fuel outlet on the sender to the fuel line to make sure the sender itself was grounded. I can't help but think a few minutes with an ohm meter would find the problem.

[69dc]

I ordered a new sending unit and when it arrived it was the wrong one. No return line on it. So I reinstalled my old sending unit and bought a Mopar ground strap for it. Connected it from the 3/8 outlet tube on the sender to the metal fuel line and still no gauge readings. If I connect my ohm meter from the outlet spud on the sending unit and the other probe to the ground I get a reading of 28 ohm which would be about right for the fuel that's in the tank. So I'm confident the sending unit is working. What still doesn't make sense to me is why the gauge works if I ground the sending unit wire at the tank end and get a full tank reading.

[poppa]

I too have a post on the fuel gauge thing    . Not trying to steal your post but this is really p_ssing me off. Bought 2 sending unit made by different manufacturers. Hooked up to gauge wire and one went to 7/8 of a tank other to 3/4. Stuck the 7/8 one in (thinking it's as good as it's gonna get) and low and behold ....it only goes to 3/8. Did the gauge test ,goes to full. How ,exactly , do you calibrate these evil things from hell? 

[Dino]

More resistance equals a lower reading on the gauge, less resistance equals a higher reading.  When there is no resistance there's nothing stopping the needle from going to the full mark, or beyond depending on calibration.  When you ground the sender wire, you remove the resistance and the gauge reads full.

The real question is, why does the gauge not work properly when obviously both the sending unit and wire are operational?  I don't suppose you're up for removing the fuel gauge?  It would make this a lot easier, not to mention you'll be able t calibrate that gauge to read spot on.  I took my time doing this and my gauge reads accurate to the gallon.

[Dino]

I too have a post on the fuel gauge thing    . Not trying to steal your post but this is really p_ssing me off. Bought 2 sending unit made by different manufacturers. Hooked up to gauge wire and one went to 7/8 of a tank other to 3/4. Stuck the 7/8 one in (thinking it's as good as it's gonna get) and low and behold ....it only goes to 3/8. Did the gauge test ,goes to full. How ,exactly , do you calibrate these evil things from hell? 

Poppa there are two small holes in the back of the gauge.  Inside are two toothed cams that move the base position of the needle.  By inserting a small screwdriver in one of the holes, you grab the cam's teeth and force the needle one way.  The other cam moves the needle the other way.  You can use resistors to calibrate but I used the sender itself on a bench.  I calculated the mid point of the float arm and calibrated the gauge to read half.  Then I lowered the float arm and tweaked the needle to read empty.  Then I moved the float arm up and the needle read just under full.  Now you adjust each cam until the needle is where it needs to be.  Turned out that because of the design, at mid level the needle would be slightly to the right, and I mean slightly.  A full tank should also give you a reading beyond full and an empty tank beyond empty.

[poppa]

Dino , I take it you make the adjustment with the power on?? I may drop my steering column and attempt this as I invested in an electronic voltage limiter and may be able to just move my cluster some??? Need to get to this tomorrow as I will find out the results of my mri Tuesday and am past being hopeful. Possible rotator cuff. They have been screwing around with this since it happened the middle of May. Thanks for all the help!

[69dc]

Where did you buy your voltage limiter?

[Dino]

Dino , I take it you make the adjustment with the power on?? I may drop my steering column and attempt this as I invested in an electronic voltage limiter and may be able to just move my cluster some??? Need to get to this tomorrow as I will find out the results of my mri Tuesday and am past being hopeful. Possible rotator cuff. They have been screwing around with this since it happened the middle of May. Thanks for all the help!

Poppa I'm in health care, shoot me a pm if you want to talk about your issues, I may be able to help.

Yes you need power to the cluster.  Is the electronic limiter a stand alone unit?  I used the actual voltage limiter to test mine, seeing that it was the one that would actually power the gauges.  Either way will work.  You could measure the output on the limiter you have in the cluster and match it with the stand alone.  And as long as the readings are close, the gauges will calibrate fine.

You could put power to the gauge with it still in the car, but you won't be able to calibrate it unless you remove the gauge.  Honestly, once the column is dropped it won't take much to remove the whole cluster.  But I understand you don't want to go there, I'm not a fan of it either!

[poppa]

69dc , I got mine through Mega Parts. I think they are made by Charger Specialties. A lot of places have them (on the internet).

Dino , I will pm you later. We are at our camper and it's like I have dial up again. Thanks

[69dc]

Thanks, I have one coming. I think the one I got from Autozone is the old style and it is working erratically.

[69dc]

Well that didn't fix my problem. It did make the oil pressure gauge more stable. Before the needle bobbed around quite a bit, now it's steady. But still no temp or fuel gauge readings.

[Dino]

Well that didn't fix my problem. It did make the oil pressure gauge more stable. Before the needle bobbed around quite a bit, now it's steady. But still no temp or fuel gauge readings.

Have you checked for continuity on the circuit board?  I learned that it's a good idea to solder the pins to the board, even when they feel tight.  It solved all my cluster issues, and there were a few.    :yesnod:

[69dc]

I just spent a few minutes under the dash with my voltage meter. I learned that I have about 5 volts on all four pins of the two gauges, the temp and fuel. What does that tell us?

[resq302]

5 volts is what you are supposed to have with those gauges.

[69dc]

5 volts on both terminals of the same gauge? I can understand the 5 volts on one leg but not on the leg that the sending wire connects to. Am I wrong? I pulled the cluster out again because I can't find a reason why the temp and fuel gauges don't work.  How can I test the gauges while they are on the bench?

[resq302]

each of the gauges should be getting 5 volts and the resistance of the sending units is what makes the gauge work and completes the circuit.

[Pete in NH]

I just spent a few minutes under the dash with my voltage meter. I learned that I have about 5 volts on all four pins of the two gauges, the temp and fuel. What does that tell us?

Hi,

That would tell me that you don't have the sending units connected to the gauges. If you did you would see 5volts on one gauge pin and something lower on the other. Do you have a factory service manual for your car? You will find information on how to test the gauges in the manual. You can use some fixed resistors in place of the Chrysler test set in the manual. also, look though the instrument restoration thread at the top of this electrical section on testing the gauges and how they work. I suspect you have some open connections somewhere and wiring diagrams will be needed to track them down.

[69dc]

When I tested the gauges they were installed in the car with the sender wire connected and the key on. I got 5 volt readings on both pins of the temp gauge and the fuel gauge.

[Pete in NH]

But, the question remains- are the sending units electrically connected to the gauges? And, are the sending units all grounded properly. 5 volts on both sides of the gauges tell me all the gauges have no current flow through them. As a test, take the temperature sending wire off the sender and quickly touch the inner metal connector to ground. The gauge should start to move quickly toward hot. Don't do more than just briefly touch the wire to ground or you could damage the gauge if things are working. If  the gauge doesn't move something is not connected or the gauge is bad.

[69dc]

You'd have to go back in this thread to read everything I have done to test these gauges, including testing the sending wire from the tank to the gauge and getting a full reading. I also tested the temp gauge by grounding the sending wire and got a full Hot reading. The temp sender is grounded by the engine block and the fuel sender is grounded by a new Mopar ground strap on the fuel lines.

[cdr]

the temp sender IS bad