Another gas gauge problem

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JohnnyDart273

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Ok, so the gas gauge in my 67 Dart 270 isnt working and hasnt that I can ever remember. I put in a new sending unit because the old was in terrible condition, but Im not sure its the gauge or sending unit. This is because the wire that runs to the sending unit (The one that pulses steadily when tested) sometimes has power and then other times it has no juice at all on it. So Im wondering if anyone can tell me what my problem with this wire may be, if I can solve this problem then I can move on to testing the gauge itself and putting everything back together. I also posted this in fuel and air as I wasnt sure which this exactly fit.
 
The voltage limiter feeds BOTH the fuel and temp gauges. Here's a roundup of the problems with my 67 cluster:

Several of the harness to PC board connector pins were broken clear off or loose. Mine was in such bad shape, and I did a partial rewire of the car, so I went down to RadShack and got some "Molex" style connectors. I simply soldered pigtail wires to the copper traces near the pins, and ran them to each Molex connector half

If your pins are not too bad, you can clean them with a small brass brush, and resolder them

The nuts on both gauges were not making contact with the PC board. Loosen/ tighten the nuts, or replace them with "real" nuts, and clean the PC board

The brass springy fingers which form the "socket" for the voltage limiter were not making good contact with the PC board. Solder short jumpers from each brass contact to the board traces

In addition, generally clean the board, clean the contact fingers on the dash lamp sockets or replace them. Bend the socket fingers out for better contact

Don't forget the sender wire and connectors itself may have problems. The sender wire connector may be loose, corroded, or the connector in the kick panel where the rear harness comes forward under the sill plate may be loose/ corroded.

If you can determine the sender is OK, or substitute a resistor for the sender to check the gauge,

Here are the approximate resistances for Mopar senders, either temp or fuel:

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

If you can determine the sender wire is OK

If you can determine the temp gauge is OK which means the voltage limiter is OK

If you can determine that the jumper across the boards which supplies gauge power to the fuel gauge is OK, and that the nuts are tight, making contact,

then last, the gauge ITSELF might be bad.

ONE WAY to check by substitution is:

1 The fuel and temp gauge are the SAME movement. You can temporarily unhook the temp gauge sender wire out in the engine bay.

2 Disable power to the fuel gauge by removing the NUT on the POWER side stud.

3 Then run a clip lead from the sender stud of the fuel gauge to the sender stud of the temp gauge. This will cause your temp gauge to read fuel!!!

IF the temp gauge worked OK otherwise, doing so should give you a clue as to whether the fuel gauge itself is good/bad.
 
Ok thats a start, Well the temp gauge still works and the sending unit is brand new So Im thinking maybe a loose connection somewhere.
 
If my memory serves correct, your inst' panel has 2 connectors on serate sets of contact pins posistioned in staright lines. Loose pins on those boards are just as common as any other. I would go behind the left kick panel and check that connection and test there also.
Leave a meter on the dash side of that connector and see if the limiter voltage comes and goes there. If it does the next spot to check would be the contact pins on the back of the panel.
 
Okay so check the left kick panel connector and then gauges. Were not sure if the possible break in the line is at the gauge or between the connector and the tank though so we came up with an idea to see which wire runs to the tank (as we havent been able to figure out with the wire only getting juice when it wants which is the sending unit wire) and see if the short is in the section from the tank to kick panel and I'd like to know what you all think of this idea and if we may blow something else up if we do it. What if we unhooked the kick panel connector and unhook the wire from the sending unit and then put a current on that one wire? Thatshould tell us which wire in the connector is the sending unit wire and if none light up when tested that the break is in that section. Right?
 
Man, yer "stuff" is kinda hart to read. I believe the answer is "yes."

I think what you want to do is................

Unhook the kick panel connector and the sender at the tank, hook a little power to the sender wire and see where it shows up in the kick panel connector

NO NEED to do that. That's what wiring diagrams are for

In the partial of the panel, the sender wire from the gauge is the bottom one coming off the gauge to the left, to the panel connector (the inline connector) and is "G4" which is dark blue, and goes to the kick panel connector.

In the partial of the rear harness, the connector at the far bottom left is the kick panel connector. You can see that "G4-18DBL" goes to connector terminal no1, at top right of the connector

You should be able to identify that wire there, ohm it from there back
 

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So I've been told. I apologise for that, I tend to type in my accent and it doesn't help I'm going to college for collision repair and not electrical systems lol. Thanks for the diagrams, I hadn't had any luck finding the right ones. Ill get on this tomorrow sometime and let you know how it goes.
 
Something else to check is the bonding strap between the gas tank nipple and the hard line that goes forward. This acts to complete the circuit for the ground side. Remove, clean the strap and nipple/hard line, and re-install. This fixed mine.
 
My car never had that when I got it so when I started the work on the gas gauge I custom made one, but thanks for trying. I didnt get to pull the instrument cluster today though, after putting the tank back in and making sure everything was right the old gas line finally went. So Ill have to hold off on checking the gauge till I get new steel line run from front to back.
 
If you want to avoid pulling the cluster, you can test things at the kick panel connector. On the dash side connector terminal 1, connect different resistors to ground to simulate what the fuel sender does, and verify that your dash gage works correctly. On the body side, measure the resistance from terminal 1 to ground to see what the fuel sender is doing. Smart to replace the dash Vreg with an electronic one (many posts on that).
 
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