While driving along the interstate this weekend my jeep suddenly lost power and threw a check engine light. It wouldnt accellerate well and seemed to have no power, and even stalled out completely on me once. I figured it might be air in the fuel filter since I have read about other's similar experiences on this forum. Sure enough it had a lot of air in the filter when I bled it out. The issue is that it only takes about 5 minutes of driving to get back to where it has so much air in the filter that it stalls out.

For reference I have a new updated mopar filter head installed, a kennedy diesel lift pump mounted near the tank, and 3/8 rubber line from the tank to the pump and from the pump to the steel line on the chassis. The engine code indicates a large leak in the fuel system. Im not losing diesel anywhere that I can see, so I assume that it must be sucking a lot of air from somewhere. My mechanic is going to check the lift pump for correct function tomorrow, but I dont know where else to tell him to look other than at the rubber lines for a rubbed through spot. Could the pump be sucking air from the in tank pickup? Or could a clogged fuel filter do this as well? (I installed a new filter about 1000 miles ago.)

I had an issue like this. For me, I had too much of a bend in my hose and kinked. Not sure if the kennedy is a pass through pump in case of failure, but make sure it is pumping and the line isn't obstructed.

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2006 Sport, GDE FT Eco Tune, Custom Trans Tune
2015 Ram 1500 Big Horn EcoDiesel, GDE Hot Tune

I may have to run new lines. Are there any good rubber fuel lines that are less likely to collapse or kink?

The days of just grabbing some fuel line at any old parts store are long gone particularly in today's market what with alcohol in gas and biodiesel both of which can be really hard on hose. Been there done that and seen "fuel rated" hose crack or turn to mush in short order.

IMHO your best bet is a local marina or marine products store (ex. West Marine) or possibly an RV place or some such place that deals with diesel engines. A good hose meets SAE J1527 type A1-15 marine (USCG) specifications and the hose is typically describe a "Low Permeation Fuel Hose has a special design NBR tube with an embedded plastic barrier layer to limit permeation. The design of this hose provides easy coupling insertion and the NBR/PVC cover is weather and UV resistant. The hose is also polyester reinforced and fire-resistant. This hose is primarily used for fuel feed (gasoline up to 85% ethanol blended fuels/diesel/bio-diesel all blends). The temperature range is -20°F to 212°F."

Not cheap - like $6 per foot for 1/2" ID but it will last and is reinforced enough that it shouldn't kink easily. The USCG specs may be overkill for our use but I'm happy to deal with a fuel hose that's designed for systems that can blow up if a hose goes bad during use.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

If your pump is working the air has to be entering between the tank and pump.

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Atlantic Blue 06 CRD Limited (his)
Joined by a 2000 XJ Classic (hers)

If your pump is working the air has to be entering between the tank and pump.

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Atlantic Blue 06 CRD Limited (his)
Joined by a 2000 XJ Classic (hers)

Well there is a new development tonight. My mechanic got done checking things and here are the results: Negative pressure (vacuum) at lift pump outlet. Amount of fuel the pump pushed out in 20 seconds: about 4 tablespoons. When vacuum was applied to the line from the tank, lots of fuel flowed out. To sum it all up: the restriction is in the lift pump itself. This is odd because the kennedy diesel pump is a flow-through design, so it shouldnt have any restriction. Im not sure how it could be blocked other than something getting stuck in the pump somehow. I am having the mechanic take the pump off and I will check it out myself tomorrow. I hope the pump is still good, it is only a couple months old.

At only a couple of months old If you have the reciept or the store keeps warranty information take it back and get a replacement under warranty

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Atlantic Blue 06 CRD Limited (his)
Joined by a 2000 XJ Classic (hers)

I just wanted to follow up on this, in case others have the same issue. Im now sure it was not the lift pump, because it stalled out again with the lift pump removed. That left the line from the tank as the only possible problem area. I dropped the tank and found where the rubber line had gotten pinched between the body and the tank, and this caused the hose to collapse under vacuum, causing the pump to suck air. I ended up buying a better quality fuel line, routing it to the pump differently to avoid sharp bends, and putting a protective liner around it. The jeep has run great for the last 100 miles, so I believe the issue is solved. For future reference I used parker 801 multi purpose hose, as it is vacuum rated to 28 inches. Other good candidates that are available are sae100r3 rated hydraulic hose and marine fuel line.