69 super bee gas gauge repair

[cudascott]

Trying to get the gas gauge working in my bee it hasn't worked since I've owned it. First I checked the gauge by grounding the sending unit wire to the chassis
then turned on the ignition switch and the gauge goes to full. So I dropped the tank and removed the sending unit to test and it is bad upon further inspection
of the sending unit the resistor was burnt. I got a new sending unit to install and decided to test its accuracy before installing it in the tank. I first check the resistor value with the fluke meter, in the empty position had 78.8 ohms and full
was 8.7 ohms. I then got under the car and grounded the new sender to the chassis and hooked up the sending unit wire to see what the gauge read at empty and full. Empty gave no deflection of the gauge and full only moved the gauge to E:violent1: so ice checked the voltage to ground at the sending unit wire at the tank and had 11.6 volts and voltage at the battery was 12.3 I verified the ground was good at the tank. So what gives! This has me scratching
my head as to what else could be wrong. Does that voltage at the tank seem normal? Any ideas would be really appreciated.

 

[67Dart273]

I keep trying to preach to people to treat these as an "end to end" system, not just a part here and a part up there

There's been many posts regarding poor connections at the harness connector to the PC board. I'm not familiar (been too many years) since I've seen a B cluster, but on my 67, the board connector contacts which the IVR plugs into were not making contact

The IVR itself could be bad or out of cal

Voltage you measure at the sender is meaningless. Your meter is very high input impedance and won't load the circuit enough to pull it down to what the voltage might be.

The IVR is originally a mechanical device similar to a flasher. It pulses battery voltage to an approximate 50% duty cycle. This in effect generates a slow pulsing on/off wave, which you don't "see" on the gauge because the react so slowly.

Also, the gauge studs/ nuts could be loose / corroded at the board, and it's possible that the connector in the kick panel could be loose/ corroded, or even the terminal right at the sender could be broken internally or corroded.

This is a good read:

(Thanks Pompis, a member here)

http://www.forabodiesonly.com/mopar/showthread.php?t=234045

I shamelessly stole part of one of his photos. This shows the contact fingers in the PC board where the IVR fits. These are crimped in, and need to have jumpers soldered across on some boards in order to make good connections

 

[cudascott]

The IRV and/or the sockets could be the culprit since the oil and temp gauges don't work either
thanks for the help I will pull the cluster and check it out. Is there a way to test
the IRV ?

 

[67Dart273]

I didn't catch that the other gauges don't work, a very important clue.

The way to test the is if it's original, just replace, then test "working" beow. Replace with a modern solid state one, RTE sells them

http://rt-eng.com/rte/index.php/Main_Page

Get yourself some test resistors or if you have the (working) fuel sender out, you can adjust it for different resistances. After you repair the board connector pins, retighten the gauge studs, inspect and repair the IVR socket and replace the IVR, "rig" the cluster up to power and hook a test resistor to each gauge sender terminal to ground. Oil, fuel, temp gauges are all same movement. 10-15 ohms gives you full, 23--25 ohms 1/2 scale, and 73--75 ohms or so for empty.

One way, example to get a 1/2 scale test resistor is go to Rad Shack and buy a 4 pack of 100 ohm, 1/2 watt resistors. Wire all 4 in parallel, gives you 25

 

[cudascott]

Cool I have loads of resistors at work thanks for the link to the solid state IVR
I will pull the cluster tomorrow evening and get to work on it and trash the original IVR. Thanks for your help I knew you would be the one that could help
Scott