Sender Unit? Gauge? OR??

[Bodie]

Bit of an odd one on the 80........ been using the truck over the last couple of weeks and the fuel gauge decided to pack up.

Not uncommon, had many a sender unit die over the years, but this time, although the gauge pointer no longer moves, the low fuel light eventually came on, so can only assume the fuel level was low!.

However, generally, when a sender dies, nothing registers on the gauge! So, I was wondering if anyone had experience of the actual fuel gauge needle packing up, but with the low level light still working?

 

[Gav missin]

Could the float possibly be stuck. Or even come off the sender. Just a simple check first.

 

[Grimbo]

Bit of an odd one on the 80........ been using the truck over the last couple of weeks and the fuel gauge decided to pack up. Not uncommon, had many a sender unit die over the years, but this time, although the gauge pointer no longer moves, the low fuel light eventually came on, so can only assume the fuel level was low!. However, generally, when a sender dies, nothing registers on the gauge! So, I was wondering if anyone had experience of the actual fuel gauge needle packing up, but with the low level light still working?

I've come across tractor senders that have a separate low fuel light part ... so it is feasible for what you describe to happen ..
Best thing is to take the plate out and just put the sender wire to earth....only do it briefly but it should then put your gauge to full...this will go some way to diagnosing your fault.
Also if the gauge is reading empty it could just be corrosion on the wires..... full is normally low resistance and empty high resistance .

 

[Towpack]

The wiring diagram shows two seperate feeds form the sender unit, one for the gauge and another for the fuel light.

 

[Bodie]

Also if the gauge is reading empty it could just be corrosion on the wires..... full is normally low resistance and empty high resistance .

Thanks Grimbo, appreciate that...... trouble is, to get to the sender, I've got strip out all the kit, fridge, floor etc again! So it'll have to wait until I've more time!

 

[Bodie]

The wiring diagram shows two seperate feeds form the sender unit, one for the gauge and another for the fuel light.

Thanks @Towpack ..... so, out of interest, is the low level light not connected or part of the resistance coil mechanism, but actually a separate float type switch?

Because if so, I'll probably, just live with the warning light until I've enough time to rip everything out again!

 

[Bodie]

Hi @Gav missin ..... if I'm honest, that's exactly what I've been thinking aswell. Just can't contemplate ripping everything out again, following my fuel issue, that your probably remember I had last year!!

 

[Gav missin]

Yeah I do. Find a bumpy rally stage track somewhere and have a spirited drive. If it don't work at least it will be fun...

 

[Bodie]

@Gav missin .....it might have to wait untill May then, at your Thetford weekend!

 

[HDJ79R]

Thanks @Towpack ..... so, out of interest, is the low level light not connected or part of the resistance coil mechanism, but actually a separate float type switch?

Have replaced LC senders before myself.... Same float and arm operates against both the variable resistor, and is also a switch contact that is is separate. The commonality is that the arm is ground. The wound wire part that is the variable resistor just plumb gets worn through.