Fuel Gauge - Goes off scale

[Simon_P]

Fuel gauge

My fuel gauge reads off the scale.

Ignition off it reads 0
Ignition on the fuel light comes on then goes out as normal, but the fuel gauge goes straight past full.

How do I check if it is the gauge or the sender? What should the resistance or voltage be?

Hope someone can help with info before I start taking things to bits.

Thanks,

Simon

[Doug]

FYI I had this exact problem and the cause was faulty tank sender = get new tank sender unit.

can't remember the troubleshoot but I measured the voltage of the sender wires at the tank to confirm it was the problem.

[Simon_P]

Thanks Doug - Luckily not that serious.

I had the fuel pump/sender out today.

The float had got stuck in the fully-up position (not quite sure how). Banging on the tank didn't release it.

The symptom was a full reading which is off the scale - which is higher than it usually goes.

Anyway for anyone who needs to test the sender in the future:

The resistance increases as the fuel level decreases.

In the full position the resistance is 38 ohms.

Simon

[GeoffSmith]

Simon,

Any idea what the resistance is on empty?

Geoff

[Simon_P]

Sorry, I don't remember.

I did measure it but didn't write it down!

Simon