Re: [FWDLK] gas gauge questions

I built a variable resistance system from small, cheap variable resistors at Radio Shack to simulate the sending unit. By substituting this in place of the sending unit, one can determine which end of the car the problem is at. For my ’55 Chrysler, the following calibration was developed: Empty 72 Ohms, ½ 35 Ohm, Full 10 Ohm. I also found the signal wire running on top of the trunk floor and under the carpet was much the worse for wear, so I black-taped it to clean up the signal.

Rich Barber

Brentwood, CA

From: Forward Look Mopar Discussion List [mailto:L-FORWARDLOOK@xxxxxxxxxxxxx] On Behalf Of Tom Stroup
Sent: Friday, August 18, 2006 9:45 PM
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Subject: Re: [FWDLK] gas gauge questions

Try the easy stuff first.

Broken wire or loose connection.

Uneven voltage getting to the gauge in the dash.

I wish I knew good answers to your questions about the gauges.

Tom S

From: Forward Look Mopar Discussion List on behalf of Jan & Roger van Hoy
Sent: Fri 8/18/2006 10:33 PM
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Subject: Re: [FWDLK] gas gauge questions

Ok, here's what I've heard so far---

my expectation is poor contact in the tank unit. on and off contact would make it jump a lot. Just a little fuel movement would move it just enough to flutter.let car sit for an hour and then turn switch on without getting in or jiggling the car. Bet is doesn't move them but still could if at right point.

You lose. The needle jumps back and forth without even getting into the car.

Rock and roll of the fuel against the float.

See above

varnish build up on the resistance wire in he sending unit in the tank. Try adding some carb cleaner to the gas or remove the sending unit and soak/rinse in acetone or lacquer thinner.

Maybe we're on to something here. But standing still?

Faulty fuel gauge..time to remove and repair, or find a replacement.

Ahh, that leads me to my second question. I just happen to have a 6v '55 Plymouth fuel gauge which will fit right in. But will it work? Is the '56 12v system reduced to 6v by the voltage limiter?

So any more suggestions would be welcome...

--Roger

----- Original Message -----

From: "Jan & Roger van Hoy" <vanhilla@xxxxxxxxxxxx>

To: <L-FORWARDLOOK@xxxxxxxxxxxxx>

Sent: Friday, August 18, 2006 8:23 AM

Subject: [FWDLK] gas gauge questions

> These are probably some of the dummest questions I've asked...
>
> [1] What causes a gas gauge needle to bounce/jerk/flutter rapidly back and
> forth? This happens in my '56 Plymouth whether or not the car is moving and
> at any amount of fuel except plumb full. Seems to be too fast to be the
> float unit. [This is a hardtop; electromagnetic gauge not the SW
> thermostatic gauge.]
>
> [2] What's the difference between a 6v fuel gauge and a 12v fuel gauge,
> specifically in the '55-'56 Plymouths? Doesn't the voltage limiter on the
> 12v drop the voltage down to 5-6v?
>
> --Roger van Hoy, Washougal, WA, '55 DeSoto, '58 DeSoto, '56 Plymouth, '66
> Plymouth, '41 Dodge