Have a 96 12V that up to now has had more problems than my '93 (which I still drive w 400k+ miles). Smelled fuel the other day and found pinholes in the molded rubber hose to lift pump. Changed the subject hose and filter while I was under the hood. Pumped it up and ran fine. Next morning it was hard to start - had to pump it up. Checked everything and found fuel on braided portion of return line between filter and frame rail and replaced it with fuel injection line (as recommended in other threads). Fuel still bleeds back in 15 min! This has to be a major air leak! There is fuel in electrical connector at Pre-filter. I am half tempted to pull lines at rear and pressurize system with air and get out the spray bottle w/ leak detection soap. It seems that taking the replacement shotgun approach is just opening more doors to possibilities. I have a new lift pump in stock ( Carter upgrade) - any suggestions?

 

if theres fuel on the electrical connector to the fuel heater youve got a leak in the thing. that will suck air Ive been told.

 

mine has been this way also. the fuel system has been real touchy once a pin hole develops the shot gun aproach usually leads to more headaches.

1. the preheater - mine the stud got loose, it didnt seep or anything else because its the suction part of the system but when shut ff she would suck air into the system and loose prime. i replaced mine for $200 after spending 600 at cummins and having them rebuild it and reseal it ect trying to fix the fuel leak. turns out not only did the stud keep getting loose but the rubber that is wrapped around the wires had deteriorated and developed into a leak.

2. the washers - alot of kits come with the copper washers, i have no idea why this is but the mopar washers are coper but also have a rubber seal on the inside surface. i had a local shop chaisng the leak at one time for me they replaced the whole system with 3 sets of copper washers each time 1 or 2 wouldnt seat up. i went through with all mopar/cummins coper washers with the rubber seal surface on them just from lift pump to fuel filter line and on the fuel filter line to the injection pump and that has ended most of my hard start issues. not sure if its just me or if the washers did it but for $10 in washers its cheap insurance i dont think my engine like starting up with the bang bang of air bubbles in the lines

i wrap paper towels around fittings i suspect of leaking usually that does a slightly better job of showing things to me vs the dust and heat evaporating and masking any seepage

 

Problem solved! After talking with various "A" mechanics and trying a few common fixes, I swapped the transfer pump with the Carter upgrade. From what I have heard - if you are lucky enough to have survived this long with the original AC transfer pump, get rid of it ASAP if fuel drains back. Thank You all for your comments! Pat