This is for a 1980 300SD, 116 body.

The resreve light on the fuel guage stays on all the time. I removed to fuel tank sending unit and cleaned it and I removed the insturment cluster and examined it and checked all of the contacts.

Does anyone have anything else to try. Is there a separate sending unit for the reserve guage?

Thanks,

Tref

CHECK!!!!

No body has any ideas on this.

I did find out there is only one fuel sending unit.

Is there any way I could have missed something in cleaning the sending unit? It was not completely clean, but the contact points were clean. I was a little afraid to get too aggressive with it. I have broken the wires on others I have tried.

This is one of those problems that you might need to use a "divide-and-conquer" approach to resolve.

Divide the problem by determining whether its the fuel sending unit or the wiring and indicator light. You'd have to have a diagram of the circuit to do this properly.

But it would be something along the line of determining if the light stays on all the time even with the fuel sending unit disconnected. What I'm saying is that the fuel sending unit may be OK, but the wiring shorted somehow.

Hope this helps.

Ken300D

OK, Thanks,

I do have a wiring diagram and it is a very simple circuit. I will try just diconnecting the sending unit and see if that makes any difference.

I will let you know.

OK, I removed the connection to the fuel sending unit and the light went out. I removed the sending unit and cleaned it thoroughly. And inspected it. I could not see anything wrong. I reinstalled it and checked the light. It was still on, if anything it seemed brighter.

Obviously it is the sending unit. Does anyone have any suggestions about what to check next?