Lift pump known failure item. Mine died young. AC/Delco junk.<br>Also, overflow valve in injec pump outlet. Spring fractures, loses fuel pressure. Been there too ($70 from Cummins). Also check fuel return line for leaks. If not replaced already, guaranteed to leak (cheapo SAE R7 hose from factory rots). Won't cause stalling/low power, but lets fuel run back to tank when engine off. Hard to start after sitting. Possible air leak in inlet side of lift pump from tank, or at preheater/strainer gasket. Possible preheater/strainer clogged (been there), and/or pickup tube/screen in tank partly clogged (from bad/contaminated fuel). The lift pump can get debris from the tank, which can cause sticking check valves in the pump =&gt; low fuel pressure (my case, zero psi and stalled engine). I'd replace the fuel filter and cut open the old one for inspection. If really bad, will need to check fuel preheater assembly and maybe tank pickup. Took me most of a day to fix mine. Real fun!!! <br>Good luck,<br>Scott

 

[quote author=MnTom link=board=13;threadid=9379;start=0#90362 date=1042152113]<br>The lift pumps on the '94-'98.5 twelve valve engines aren't prone to failures. {...}<br>[/quote]<br>Sorry, beg to differ. This was common knowledge back a few years ago (on the Dodge bbs/sites). Grit/debris gets into the bore housing and scores the wall =&gt; loss of pressure. Also, there are check valves which tend to clog/stick open again causing low pressure. The pump used in the 2nd gen B motors is different from the 1rst gen, which I think used a diaphragm type. You should have 20+ psi at low idle, to 35+ psi at high idle (drops under load of course). Mine was running at 3-5 psi max @ 2000 rpm, dropping to zero under load. The oem pump is AC/Delco, but my replacement from Cummins was Carter. Although a direct bolt in, the outlet threads are offset slightly requiring bending/relocating the steel fuel line. Believe there may be other oem pump suppliers as well. <br>BTW - Mark Chapple @ TST was the first to tell me about this problem (and related COMMON overflow valve failures). TST sells a fuel line adapter to connect a pressure guage for checking your pump (replaces banjo bolt on filter housing). <br>My replacement pump now has over 100K mi on it, but pressure is steadily dropping - so will be due for another soon. Can't be helped as there is NO filter between the pump and tank - only coarse screens in the preheater housing bottom and around the pickup tube in the tank. Note - the preheater is NOT part of the lift pump: It is a separate unit. Mechanical pump failures usually gradually appear, starting as a loss of power and rough idle (overflow valve gives similar symptoms). Attached a couple pics of my dead lift pump for you amusement. Try http://www.dodgeram.org/tech/dsl/fil...filt_clean.htm for more info of prefilter details (or other related items on the page). <br>Good luck! The fuel lines are a pita to get to at the firewall, if you haven't found out already. Especially check the inlet line from the tank, where steel joins rubber. Mine was rotted.<br>-Scott

 

<br>Here's one more pump photo. Hard to tell but the wall is badly scuffed and scored. The outlet check valve was stuck open. Believe it all started from a bad tank of fuel from a brand new station. Tank was full of fiberglass shreds, rust, scale, and sand. BTW - NEVER EVER buy fuel from a station where a tanker truck is dumping fuel. All the crud on the bottom of the tanks get stirred up -takes hours to settle back (don't trust the station pump 'filters' either). <br>-Scott

 

[quote author=MnTom link=board=13;threadid=9379;start=0#90804 date=1042249676]<br>Shire<br>This is the first time that I have heard of a lift pump failure on a 12 valve. I looked at a lot of bbs about these trucks and I don't recall (good memory just short) a problem with the pumps...<br>[/quote]<br>Mark Chapple &amp; Joe Donnelly @ TST, Dave Fritz (dodgeram.org), &amp; the Mitchells @ Enterprise Diesel all told me the same thing when I was having fuel problems (lift pump &amp; overflow valve), but this has been years ago (my truck is a 95). Not saying it was a widespread problem, just happened more than it should. I think the pumps were re-designed at one point, but of course changed to electric in 98.5. The Cummins/Carter pump seems to be better designed IMO. At least haven't heard of any failures of the Carter version, so far. The AC/Delco pump is longer and less rigid. The bore in mine was worn egg-shaped, so obviously something wrong. I was going to replace the pump originally with an electric, but never found a pump w/suitable output pressure, rated for continuous duty w/diesel. Anyhow, IMHO most lift pump failures weren't so much the pump as the reverse-check valves getting stuck open. If you have a fuel pressure gauge it's easy to spot. Just my .02...<br>Regards,<br>Scott

 

[quote author=Ryan link=board=13;threadid=9379;start=0#91058 date=1042327071]<br>One more option, friend of mine had this problem, it wound up being a section of rubber fuel line was being sucked shut and starving the engine of fuel.<br>[/quote]<br>Oh, that reminds me - had a related problem: The rubber return line that runs from back of the inj pump, down along firewall rotted from the inside out. Before I knew it, lots of rubber bits &amp; chunks ended up clogging the tank pickup screen. Had to drop tank to clean out. Replaced all the rubber lines while I was at it (fun rating: -10). <br>-Scott