Fuel gauge sending unit resistor?

[Mercedesrover]

New to the board and to Land Cruisers so excuse the newb question.

I've acquired an '86 FJ60 and though most things on the truck work, the gas gauge doesn't. I pulled the carpet access panel above the sending unit and see that it's got a brand new one there. The wire plug has also been cut off and a pair of spade connectors crimped on in its place. I pulled the sending unit and its working fine, (resistance changes over the throw of the float) and if I cross the two leads the gauge goes to full. It seems like there needs to be a resistor between the two leads on the sending unit to make it work properly. Is it possible that it was part of the wire plug that got cut off? Does anyone know the correct impedance resistor to put there? Or maybe I've just got a bad sending unit with too much resistance itself.

Any help would be appreciated!

Thanks!

Jim (Usually a Land Rover driver.)

 

[Tim-HJ61]

Jim,

How do you know the problem is at the sender unit end?

My sender unit is broken, so I'd like a new one. They're pretty pricey here in Oz, so if all else fails, send me yours!!

I am pretty sure there is no resistor in the plug itself, having pulled mine apart recently. The sender is the variable resistor. When you cross the wires you say the guage works, so maybe the guage does function properly. If the guage jumps up to overfull straight away, then you've maybe there is a short to earth in the sender unit, or how it joins onto the tank. Umm, when you say you cross the wires, do you mean you join the wires together creating 0 resistance, or are you swapping + and - ve?

I've picked up somewhere that the Fuel sender unit on Empty should be 120 ohms, full 17 ohms. Maybe as you say, the wrong unit was fitted but a quick check with a multimeter will sort that out.

This is getting a bit rambling but I'm waiting up late to see Australia take on Italy in the world cup!! Check connections, and check your earth. Beyond that, send the sender unit to me for a new home.

Tim