A problem just turned up with the gas gauge on my 1950, 3604. I bought her just about on empty, and the gas gauge was working fine, it was accurate and had no needle bounce, put 5gal in to get her home and the gauge was registering ok.
Once I got her road worthy again eight months later, I ran most of that fuel out and added another 5gal, which took me up to about a third of a tank. Now, I’m kind of sneaking up on a full tank, which I didn’t want to get stuck with just incase I may have had a leak part way up the tank or a clot which required me to drain the tank.
So I ran a good bit of that load out and added 7gal next time, this brought me up to a little over 1/2 tank on gauge, still steady and no bounce. Now after I’ve bounced her around for a couple hundred miles with no apparent leaks or problems with the fuel lines clogging up I pumped in 10gal and the gauge responded showing a little over 3/4 full. This time once I got her on the road the needle started bounding between the 3/4 full point and full rather rapidly, like there was no damping. After driving it for 50 or so miles with it doing the same thing with no change, I refilled again. I had a longer jaunt planned, almost 80 miles round trip last weekend, so I decided to top it off since I had encountered no fuel system problems. It took just under 10gal to top it off, and when I could hear it up to the neck I capped her off. The gauge shows full, just as you would expect, no bounce. Now I ran out my 80 miles and she should be down a little under the 3/4 mark and I’m getting that un-dampened bounce to full again.
Key off, she goes to empty. Sitting still in the garage she shows a little under the 3/4 mark and is steady.
First thing I tried was removing all the connections and cleaning with wire toothbrush, including the ground connection under the seat from the sender. The gauges were out a couple of weeks ago and every connection was cleaned at that time. An ohmmeter across the sending unit showed that it was varying when I rocked the truck back and forth from 3 or 4 ohms up to 16 or 18 ohms.
My suspicions are that the sender has some corrosion on the resistance unit near the full position. Any more Ideas before I pull the sender out?
Denny Graham
Sandwich, IL
