83 300SD Fuel Lines & Sending unit Help

[dbdoc]

I have recently purchased a 300SD and want to install a fuel line heater and filter for using WVO. Can someone help with which fuel line is the feed and which line is the return fuel line, what about the "cigar" hose???

I have already cleaned the fuel level sender, it was at 1/4 tank when I ran out of fuel. BTW on a 83 300SD the sender is removed by taking the back seat out not the first aid box!!!

Now the sending unit will not work at all, it did before. Are the two thin wires, like fishing line, what send the signal or is it the center post?
When I opened it up it was full of gunk and one of the "thin wires" was broken.

Any help will be appreciated.
Doc

[TMAllison]

You would be better served with a two tank system or better yet burning commercially prepared B20 instead.

The fuel senders oftentimes fail beacuse of bad grounds.

[tballx]

Sorry if this is a thread resurrection but having just cleaned my fuel level sending unit and then replaced it on an 84 300sd, I just wanted to pass along that if the either of the wires are broken, it is dead. The float maintains contact with the tiny wires and completes a circuit. There is a resistor at the top of the inside of the sending unit that measure the resistance of the circuit as the float moves up and down along the wires. The movement of the float and its position relative to the wires is what changes the resistance. You can search for the ohm ratings if you're so inclined. When the float makes contact on the bottom of the unit, the reserve light will light. This flickr series is awesome if you're cleaning an unbroken one even if your doing a 300SD which as you know isn't the same removal process as the 300D.

The fuel "feed" line is the one going into your prefilter. You can trace it from there. The cigar hose is the return line from the main spin-on filter into your fuel hard-line back to the tank.