Fuel Guage Mystery

[rix116]

On my 1974 450 SEL, when I start the car cold in the morning the fuel guage goes over to FULL. After 3-4 miles, it corrects back down to the proper level.
If this was a guage or ground problem I would expect it to always be non functional.
On the other end, if the float was "sunk" w/ a hole or whatever, I would expect it to always be sunk.
This happens consistenly, every day I drive it.

Any insights?

[jrmd01]

My mom's car had syptoms vaguely similar to yours. The gas gauge, temperature guage, turn signals and the radio would work intermittently.

I thought it was a loose wire or ground, but one of my dad's friend came over and changed the fuse and now it works fine.

The fuse was burnt at the edges contacting the terminals, and not at the usual place in the middle of the fuse --- that's why I missed it.

It may or may not fix your problem, but it's worth a try. The fuse is only $0.50cents.

Good luck,

jrmd01@yahoo.com

[rix116]

Don't think it's a fuse, as this is ony happening to the fuel guage.
All other guages work full time. As stated the fuel guage is on full far right position for 3-4 miles at start up, and then it corrects to the proper reading.
Anybody else?

[2300com]

I don't have an answer, but I have an 86 and a 91 190e and both of the fuels gauges bobble when they are sitting around the 1/2 tank marker and the car has just been turned on. They too settle down after some minutes.

A hunch is that it is the indicator in the tank. I have a vespa scooter that also does this when I first take it out of storage. After I shake the scooter side to side the gauge starts working. Not as easy on a benz.

[tecqboy]

I had a 1973 non MB vehicle with the same problem. It turned out to be a corroded connection at the junction (plug) between the wiring harness and the sending unit on the tank. When I tried to clean the plug and socket, it just fell apart. The copper wire inside had all but disintegrated. Water gets into everything and when you add electricity, metal oxidises.