Fuel sender issue

[oxrod]

Hi there,

I have just replaced the fuel gauge and sender unit in my 72 Duster 340 but the gauge is jumping up and down, I then remembered that I have a 71 Rallye dash, so am I correct in saying that I need a sender unit for a 71 or is there another one for the Rallye???? Any help much appreciated as I am In New Zealand. (The freight is a killer so want to order the right one)

Thanks

 

[67Dart273]

First thing to do is "split" the problem

Is it the sender, or up front?

At least a couple of ways to do this

Check sender continuity to ground. Is there a ground jumper from the sender to ground?

Check sender resistance. This might be difficult if you cannot jounce the car while doing so.

Or.......use a substitute resistor at the sending wire to ground and see what the gauge does.

If you go to Rad Shack and buy 4 -- 100 ohm, 1/2 watt resistors and wire them all in parallel, this makes one 25 ohm resistor which should give you 1/2 full after a minute with key on

If it seems to be "up front," split it again at the kick panel connector to the rear harness and test the sender wire

 

[oxrod]

Awesome thanks, gives me somewhere to start.

 

[oxrod]

Sorry, testing the sender OHM range is easy but how to you test the gauge to see if both are compatible?

 

[d55dave]

Is the fuel gauge the only one that jumps around? The voltage limiter on the back of the instrument powers all the gauges and has caused many problems in the past.

 

[RedFish]

The senders are the same for either inst' panel.
The mechanical instrument voltage limiter is the most common cause of wild needle swings.That item is located inside the rally fuel gauge.

 

[67Dart273]

Sorry, testing the sender OHM range is easy but how to you test the gauge to see if both are compatible?

I forgot.........

Take the 25 ohm resistor I mentioned, and hook from the sender connection to ground. This works on any gauge except ammeter. Any of the gauges should give you around 1/2 scale after about a minute with the key on

Here's a thread or two

http://www.forabodiesonly.com/mopar/showthread.php?t=179517

http://www.forabodiesonly.com/mopar/showthread.php?t=264543

http://www.forabodiesonly.com/mopar/showthread.php?t=207604&highlight=gauges