Crimedog

Mine started losing prime a while ago, then it quit for a little bit, now it's doing it again. It's different every time, too. Sitting for 24 hours usually requires about 10 pumps on the primer. Sitting for a couple just makes it crank a couple times before she fires up. I already replaced the return and supply line at the engine. I don't see any wetness on the hard return line running to the injectors. My next area of focus would be fuel filter, but I wanted to ask first. Anybody else have any leaks anywhere besides the return lines?

Thanks in advance!

waldersha

Chasing the same kind of thing here. Some other suggestions are the fuel heater electrical connection, overflow valve, in tank module, check valve in the lift pump, line between lift pump and fuel heater. Haven't been able to locate mine yet.

Good luck!

Bluetick

If you have access to an electric fuel pump, place it between the fuel tank and supply line. With the engine off let it run a bit, then trace all of the fuel lines, lift pump and filter housing. If nothing shows, then check the pickup tube in the tank.

infidel

Second most common leak point I've come across after the the return line is the metal line on top of the bell housing where the hold down tab is welded to it. You need to crawl underneath and feel for wetness. It doesn't need to leak much fuel at all in order to suck air.
If it's wet abandon the metal lines and run hose all the way from the engine to tank.

I pressurize the fuel tank with compessed air, 10psi max, to chase down supply system leaks. Works excellent.

wcjp

On my 96' the fuel supply/return helped the loss of prime. I also did the fuel preheater strainer and gaskets which helped. The problem was the fuel preheater to liftpump softline. Of course no local dealer had this line in stock. The retail price of the line was excessive. I used a longer than needed fuel line and put a big loop in the line. I cut the old line in half out of curiosity. Couldn't believe the truck actually ran with the major dryrot.

arroyojim

do you remember the price? i need a new one and was going to put on just 1/2" fuel line. is that what you used? it does seem to fit but when you pull it off it seems to kind of lose some material to the "barbed" metal fitting i think on the heater side.

wcjp

I don't recall the exact price of the formed diesel line from DC. It didn't matter as no dealers had the fuel line in stock. I used 12-16" of marine grade diesel line. I left a lazy loop from the preheater to lift pump. The line was long enough to prevent any tight turns. Short enough to clear the steering. Going directly to the lift pump wouldv'e induced a kink in the line. The marine grade line was readily available at a boating supply place. I took in the old line to ensure proper inside diameter.

rharveysr

Could be the diaphram in the lift pump itself. Mine started dropping prime over night..Checked all the lines and it turned out to be the lp...replaced it and stopped the problem..

Rick

Crimedog

Would it be alright to use some of that UV die in the fuel tank?

infidel

It wouldn't hurt but probably wouldn't help. Most times fuel supply leaks suck air but don't leak much fuel.

wcjp

Have you checked the soft line to the lift pump?

arroyojim

i concur. just pulled mine off and it is all kinds of split and cracked inside with nothing visible on the outside

FarmerJon

Check to ensure the seal on your fuel filter is tight, and the various fuel filter banjo connections are sealed and tight. Due to my schedule, I had a local Dodge dealer replace my soft fuel line that goes behind the fuel filter that had pin holes in it. Doing this they had to remove the fuel filter, however, they didn't exactly put it back right. In stead of my starting getting better, it got worst until I noticed a few leaks around the fuel filter. I tightened the nut that draws the filter case to the top of the filter housing. That improved the starting. I left the tightening, etc. of the banjo connections to the dealer, in case they were cracked, etc. They messed it up, they can make it right.
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98 Dodge (mfg 11/97) 2500 4X4

Crimedog

I haven't thrown anything at it yet, when I think of it it, this last time it started after I changed the fuel filter so I'm suspecting maybe the water sensor/drain that screws into the bottom of the filter. The filter is on there awfully tight, I don't think the top of it is leaking. It sucks being at school, people get mad when you spill a quart of diesel all over the parking lot so I've got to wait 'til I go home before I can play with stuff. I think I'm going to do the line that goes to the lift pump first though. It looks like 1/2 inch, is this right?

WVAussie

Tracked my leak to the steel elbows that sit on top of the fuel sender unit where the plastic lines connect.