I need help fixing a fuel leak I discovered. There is fuel seeping about 1/4 inch above the fuel filter on my 93 W350. I thought it might be the fuel line from the lift pump but it isn't. I can dry the area and watch the leak begin once I start the engine. It is leaking directly above the sensor below the fuel line.

 

remove the fuel filter and inspect the fuel heater it is attatched to. there is an o-ring seal between this and the head. look here for more info https://www.dieseltruckresource.com/...r-t258221.html

 

That was quick. Thanks alot! I do believe that is my problem. I read that thread. Would anybody happen to know the part# for the O-ring???

 

there is a PN for a napa oil filter that has the correct seal in that thread, give that # to your local parts house and they should be able to cross it to whatever brand they carry

 

Great. I will do that tomorrow. Thanks again.

 

The o-ring that the heater attaches to the head sounds like its the one you want. I ordered mine from Cummins Rocky Mountain, the p/n is 3913695 (my truck is an '89) the part was $2, I ordered a spare.
What you describe is EXACTLY what my truck did. I replaced the o-ring and the leak stopped.