7707

I got out of the truck at work today and notice fuel dripping underneath the truck.

We think/thought it was the fuel feed line going to the fuel heater. So I pulled it but can find nowhere it can be leaking from.

So I pulled the filter feed line...from the lift pump to the filter. it too seems fine. The rubber return line from the pump is dry so I know it's not leaking. I pulled the filter housing off as well to see if it is cracked and it is not.

Where else can it be leaking from? All fittings appeared tight and dry.

1995 12 valve.

patdaly

Could be the fuel feed line or fuel return line, rubber to SS braid, then quick connect at the base of the drivers foot. They get bad over time, you don't say your location, but the steel lines also rust.

Crawl under the drivers side by the front of the cab with a flashlight, you might find it.

chariotdriver

How did you check the rubber return line from the p-pump? Does it leak while running, not running, or both? A couple of checks you can do: Pinch off the return line a bit which will drive up the pressure on everything downstream of the lift pump. If you can't find any leaks, pressurize the fuel tank to about 1-2 psi and start looking. Diesel finds the smallest of leaks with almost zero pressure pushing on it.

BigIron70

Return line most common 12v fuel leak location

7707

It leaks only when running.

I was able to check the rubber return line because I have the main feed line, filter feed line, and filter/filter housing all out of the way. It was dry as a bone. I am going to replace it anyway just to be sure and I am also replacing the short rubber line that joins the line from the tank to the fuel heater.

The only other line it could be is the hardline from the lift pump to the filter.

With the engine running you can see fuel (mildly) spraying right around from behing the fuel filter somewhere. But the top of the fuel filter and all its fitting are dry.

infidel

Sounds like the return line or a cracked fuel filter.

MrKen

I don't know how to post pics, but I removed the fuel filter to have good access, moved the master cyl over a bit too. Then I used the digital camera and took many pics. Download them and then you can zoom in, spotted my issue, and I new what I was doing. Hard to stick your head down in that area. I was amazed at how cracked the line was, If you are going to the trouble, may as well relace the 90 degree hose at the same time, not sure what is is called. The red line in Infidel's pic is good, and the camera helped me understand better. Hope this helps a bit.

7707

I must have fixed whatever was leaking. The only things in that area I did not replace was the hard line from the lift pump to the filter and then the big 90* between the heater and lift pump.

So far so good.