Chasing a Fuel Leak

[icanfixall]

For a few weeks I have smelled a fuel leak. Can't see anything in the valley or on any return caps. Yesterday drove maybe 70 miles and felt my mileage was poor. Let rig sit a few hours and drove to store and saw a trail of something leading back to my truck. Truck was parked on a uphill slop too. Came out and saw a puddle about the size on a soccer ball under the rear of the engine. So today turned on the ignition till the electric fuel pump came on and run it but no leak found. Cleaned off a dirty number 8 injector but still no leak. Ran engine but no leaks anywhere. Got under engine and found oil on the trans pan and looks like it came from the oil filter. I have always had issues with filter leaks. With the oil cooler header off many years ago I checked it for burrs or holes in the seal surface. None found. Draw filed it anyway. Still nothing showed up. So I used my 18 inch channel locks to check howe tight the filter was or was not. It was loose so I turned it another 3/4 turn. Found what looked like a loose motor mount nut. Those 18 mm nuts are tuff to get at. Tightened all 4 of them. Only one each was loose on each side. Now it rest time and thinking whats next. Still thinking about the possible fuel leak. Pump is dry too. Even the weep hole is clean. We will see later on...

 

[IDIoit]

are you still running the stock WFS?
those things are complete garbage!
thats the very first thing i learned about these year trucks. lol

 

[icanfixall]

are you still running the stock WFS?
those things are complete garbage!
thats the very first thing i learned about these year trucks. lol

Not really sure what WFS is but I'm not seeing any leaks. My filter is the stock unit from 1989 complete with the spin on bottom cover. No leaks at the filter.

 

[IDIoit]

water fuel seperator.
driverside firewall,
it has a tube that goes down inbetween the firewall and fender well
could be a weak spring inside it, the plundger could let fuel excape during operation?

 

[ZWilson07]

Like they mentioned it could be your WFS but that should be pretty obvious to see since it is right there on top.
Like mentioned it could be the rubber seal where the seperator screws on and seals to the bottom of the filter, and also three places at the bottom of it. The rubber plunger inside could be leaking and letting fuel out either where the wire plugs into the metal threaded rod underneath, the pressure release, and/or where the actual drain screw/circle that you turn to open and close the drain.

 

[ZWilson07]

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This shows the 4 spots really well. The outer seal, plus the 3 places inside that could in theory let fuel out but like I said if it was, it should be pretty obviousl be looking right under the filter with a light or puttin your hand under there. I know you mentioned the filter is dry but figured I would throw in just in case you only checked the top of the fuel filter itself or for anyone else that every checks the thread.

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[sjwelds]

Guys guys guys....icanfixall is one of the most, if not the most, knowledgeable people on the forum here. I think it's a safe assumption that he has already covered the obvious possible problems. Just sayin'

 

[IDIoit]

Sometimes you get so deep in thought you miss the stupid Lill things.

 

[ZWilson07]

Guys guys guys....icanfixall is one of the most, if not the most, knowledgeable people on the forum here. I think it's a safe assumption that he has already covered the obvious possible problems. Just sayin'

Oh no I knew it was him, I am sure he knows all about the seperator and knows plenty more than I do

But it was good info to post in case anyone else comes across the thread that don't know a ton like he knows.

 

[RavenTBK]

Fuel tank full, or recently filled when this happened?

In my case, I've got a magic leak somewhere on my tank, that lets diesel flow out, but not water. Filling the front tank between the 13-15gal marks, fuel will drip between the cab and bed, and make a neat almost solid line trail if I move slowly through the parking lot. Uphill is especially bad. I've dropped the tank, cleaned it up, and water tested it, and found absolutely nothing. I'm simply dealing with it until I get my saddle tanks welded up.

edit: NVM. I see now his fuel drip is under the engine. I overlooked that and assumed the position of the drip was unknown.

 

[88fordidi]

Fuel return line? Would be one of the only ways that you would lose fuel without losing performance/grabbing air.. also it would only leak when the engine was pumping fuel, aka why you aren't seeing a leak just by priming up the lift pump.

 

[icanfixall]

Well I still have no signs of a leak. Drove plenty today. Even drove into the same parking lot and parked in the same spot but no trail or leaks. Just not going to worry any more bout it. Thanks for all the suggestions too.