Fuel sender unit not working

For some reason both wires are reading as earth ive had a light on them and the volt meter reads nothing on the unit I know nothing about electronics but get by can anyone help I’ve also swapped the wires over

 

One is permanent - the one without the plastic surround, the one with the plastic is the - supply to the front that goes to the stabiliser by the fuel gauge.

 

Set your meter (if you've got one) to low ohms range, and measure the resistance across the sender. A test light or measuring volts won't really tell you anything.

 

I’ve set my meter to 200 ohms and it’s reads 00.09 with ignition on

 

Where are you measuring?

 

On the connectors is that wrong

 

You mean the connectors on the sender? Is the sender out of the tank?

 

It’s still connected up in the tank put the meter on the wires

 

Wires at the cab end?

 

Also I forgot to mention the fuel gauge has gone to full and back down to nothing probably about twice in 3 years for no reason upon starting the van, and no the wires on the sender it’s self

 

If you take the wires off the sender and measure the resistance directly, should be somewhere between 10 and 70 ohms.

If your gauge has jumped all over the scale, may just be dodgy wiring.

 

You cannot measure resistance with the ignition on.

 

Oh thanks it said 00.09 with the ignition on but nothing at all when I tried it with it turned off but still connected

 

Disconnect the wires from the sender, then measure the resistance on the sender terminals directly.

 

Thinking about it I’m pretty sure I tried that and it read 0

 

Does the reading of 0 mean the sender is kaput or is it the fact both wires being earth shouldn’t one be a live

 

One should be live. Maybe the wires on the sender are switched around. The earth one is straight on the metal, 12v one on an insulator. Earth wire should be short towards the engine. Gauge wire off to the right.

 

cheers I thought so do you know where the live actually goes, would I be able connect a wire from another ignition live to the sender and gauge, or would that achieve nothing.

 

Again, are you measuring the resistance with the sender completely disconnected? If the sender's disconnected, there won't be a voltage anywhere - it's not a voltage source, just a variable resistor.

The "live" connection to the sender (from the wiring loom) comes from the dashboard end of the cable, via the fuel gauge.

 

Sam,
The circuit in layman's terms.
12v from fuse box to voltage regulator
Voltage regulator to gauge
Gauge to sender
Sender to earth.