Haven't checked yet. My tank is a custom build (42 gallon) and kinda a bear to remove.

 

Are the O-rings the leak culprit? I am having problems with fuel starvation.

 

Looking for quick delivery on fuel line rated for biofuel mix that can be delivered quickly. Not happening. I was looking to run the new lines this weekend. Maybe order it from O'Reilly's and just get a roll.

 

Not familiar with o-rings on a diesel. But I'm presuming that they leak air and thus cause the pressure issues which then cause fuel starvation.

 

Snap on fittings on the lift pump, and the fitting coming out of the tank. I suppose I could just pull the old O-rings out of those fittings and replace them. Use some Viton O-rings. The lines themselves are nylon.

I bought a 2 rolls of Hydraulic/fuel lines. 5/16th for the return, and 3/8" for the supply line. The guy at NAPA had no idea what the specs on his line were. "I can't look it up." I came home looked for the Gates hose and called them up with the Gates number and they ordered it. It is good up to B20 rating. $110 out the door for 2-25ft rolls. I am hoping this will fix the problem. Then it's on to the next thing.

 

Not sure about the lift pump, but the tank was pulled, drained and the seals examined with a new line installed from it to the secondary fuel filter I have under the truck, attached to a frame rail. The last time the truck failed, it didn't feel like other times thus I went to that secondary fuel filter, opened the bleeding screw and a rush of air came out. Starting up and worked for a minute before failing again. Then I ran the truck while bleeding that portion of the line via the 2nd filter. Hasn't failed since.

This issue is so long standing that it's hard to determine which portion of the fuel system is failing.

 

Stock fuel tanks are vented. Generally when air is introduced into the fuel delivery it's caused by a partially clogged pickup screen in the tank. The snap lock fuel connectors are only meant to seal under pressure NOT vacuum. That's why modern vehicles have the lift pump inside the tank. Often what happens is when people add fuel additives they loose the foil seal into the tank. These will fall away from the pickup screen when the engine is off and get reacquired when running. This makes for an intermittent PITA! Don't ask me how I know...

 

Issue SOLVED! Back in Oregon I found a good (aka talented and curious) mechanic that dropped my tank and found a nickel sized piece of laminated cardboard (probably from a fuel additive cap) that was periodically blocking the fuel intake system when the tank got below 10 gallons. That's out, the systems been tested and made air free and now all's well in the world again.

 

Dang, such a simple small thing can cause a lot of headaches.

Glad you found it and thanks for letting us know.

 

BTW, the key to your success was the talented and curious mechanic. Someone that can actually think with their own brain instead of just doing what the computer brain tells him/her.
Perfect example of Mathew Crawford's "Shop Class as Soul Craft" in action!

 

I'll wait for a little time before celebrating with you.

 

Hmmm, Rug Trucker may be a bit more pragmatic. Not to be a downer but isn't the little cardboard seal relatively small compared to the intake screen area?

 

A while back I cut a hole in the bed to get to the fuel tank unit. When I pulled it out there was a ton of crud coating the screen. I cleaned it off but there is probably more in the tank. I still have the same issues as you in that I lose prime after the fuel level gets down to 1/2 tank on the gauge. When it warms up and I can work on it again I'll drop the tank and give it a good cleaning and run the remaining fuel through a filter to get out the floaters.

Edwin