Anu one that have any suggestions?

My gauge only goes to the full when turning the ignition on and only moves down apc 5-6mm when tank is empty.

I guess thats its the pick up unit thats causing the trouble but there is no obvius faults on it so i figured that it might be able to measure resistance on it. But where shall i measure and what shall it read?

And anyway how can i check the gauge?

The sender works by sliding a contact over a variable resistance (usually wire-wound rather than carbon track type) IME. This isn't actually reparable unless you can find the correct gauge of resistance wire. I'd suggest letting the tank run well down, then giving it a hefty thump with the palm of your hand to see of this unsticks the float side. If it does, apply a little graphite lubricant (picked because it's not soluble in petrol) to the sender pivot. If it doesn't, I think you need a new sender.

Actually i already had it removed and have taken it apart, nothing have been stuck and it looked good thats why wondering about the resistant values to see if its the pickup or the gauge that the fault.

My experience is that they usually either stay stuck on "empty" (leak in float means it doesn't) or work fine for part of the travel then drop suddenly (broken track, and dependant on which end is live which way they go, either full jumping down to half or half dropping to empty in no time flat).

My other reason for changing the sender first is that it's likely to be way cheaper than working on the instrument board! And I always go with the cheaper of 2 alternatives first if I can't see a good reason why it would be the more expensive one.

Sounds like the wiring has shorted somewhere, Trace it back from the sender to inside the car, you will probably find some of the wiring sitting in a pool of water

Only if there's a connector there or thereabouts surely? Wiring sheathing keeps water out as well as keeping the electricity in!

Only if there's a connector there or thereabouts surely? Wiring sheathing keeps water out as well as keeping the electricity in!

If only that were true. Ive spent thousands of pounds on truck wiring looms that were corroded with no visible point of water entry, Dont forget, by capiliary action, water can creep through a wires insulation in a matter of days

If only that were true. Ive spent thousands of pounds on truck wiring looms that were corroded with no visible point of water entry, Dont forget, by capiliary action, water can creep through a wires insulation in a matter of days

I'm familiar with capiliary action, and still say that, with modern PVC wire, the point of ingress must be a break in the sheathing (well unless the vehicle is Italian ).

i got it working now.

took apart and cleaned all parts in the pick-up its supposed to be apx 400ohms between the yellow and the blue wire the black in the middle is the reader for the warning lamp. When the pick up is manouvered it will go from 400ohm(full) to 0ohm (emty) measured on one of the wires and earth.

Then i measured at the gauge on the wires and manouvered the pick up to se that the cables is ok, and found out the the gauge is faulty.

Took the gauge apart and found that one of the leads may have shortciciut on another or bad soldering. anyway moved the isolation and resoldered the wires all of them then it worked:-)