Fuel Sender Troubleshooting

[Swiss_Toni]

Before I go and buy a new fuel sender(s) I was wonder if anyone has any tips in troubleshooting the fuel level system?

I've got the original VDO tube type sender and stack gauge (which can be calibrated to sender).

I calibrate the gauge (I've done it a number of times) but other than full it really doesn't show the correct fuel level, especially on part tank.

It's the same on both tanks.

Any thoughts, do the senders sometime "go"?

[Swiss_Toni]

Interesting....

As both side are reacting similar and I don't believe at this stage it's a sticking sender (sloshing).

That leaves wiring...

There are two senders, 1 gauge and a switch. I switch between the tanks which operates the low pressure fuel pumps (1 for each tank) and selects which sender is used.

[Swiss_Toni]

Thanks for the tips.

1st step, breakout the multimeter

I'll take the switch out of the equation and maybe "slave" in some wires to eliminate that as an issue if there still is a problem.

[Swiss_Toni]

Richard at the factory has been helpful as alway.

Among other things he's provided the figures for what the sender should read.

Full is 2.1 ohms
Empty is 71.9 ohms

I did VERY quick check directly on the sender and I got 3.9 ohms at full and 54 ohms with about 10l in the tank. The resistance moved smoothly as I filled the tank.

More troubleshooting is needed.