I have a 94 4.9 with duel tanks. I just put a new pump and fdm in and am trying to wire it up. I have two ground wires (thick black, and smaller grey w/red stripe) that need to be identified on the old FDM in order to wire it to the new FDM. I need to know which is the pump ground and which is the sender ground. Im sorry I cannot tell, I am electronically illiterate.

 

The pump should just have 2 wires, one black and one red. Red will be you're power wire and the black should be the ground.

The sender has its own two wires but don't interfere with the pump.

 

Just clearified in my original post that im wiring in a new fdm unit not just the pump.

 

You should have 4 wires in total, 2 for the pump and 2 for the sending unit. Is this a universal one you are installing? Cause it might not work with different resistance values.

 

yes there are 4 wires. A pink w/ black stripe and yellow with white stripe which are the pump power and sender power respectively. The two grounds are grey w/ red stripe and black. Im not sure which is the sender ground and which is the pump ground.


I just want to make sure because i suspect the directions from the manufacturer to be incorrect.

 

So long as you have correctly identified the sender and pump feed wires the grounds matter not, just ground them. Ground is common.

 

Here this should help, either way both grounds end up going to the same place so wouldn't matter which way you wired them.

 

Thanks a lot. I was just worried because one ground wire looked thicker than the other. I thought it made it would make a difference.

 

I used the thicker gauge wires for the pump and the smaller for the sending unit.