Purchased a 02 2500 2wd automatic Vin 6 Cummins last year. Nice truck, used with a 5th wheel to tow a camper previously. Nice 'cause it kept it out of the Iowa salt!!! 80k miles and want to run a second fuel tank in the bed. May try to centirfuge used motor oil for "black diesel" later, but I want to run a separate tank instead of filling into the main tank as many do. Truck had the lift pump on the engine removed and a new sending unit with an in-tank pump installed by a Dodge dealer a couple of years ago. Not finding much info on how this was done or part #s. Has an aluminum block in place of the original Carter type pump on the engine. Don't see any wiring added to run the in-tank pump? Would that wining have been present in the truck already? I have always heard in the drag race community that the pumps will "push" fuel better than they will "pull" fuel, but I can't imagine that little pump in the tank is as good? The engine mounted pump would make switching tanks easier, as I would just need to plumb up a 6-port switching valve and wire up the sending units so they switched at the same time and draw from either tank. Truck is stock with no mods so I don't need additional fuel. I guess an additional pump by the auxiliary tank would be a plus if there was ever a problem with the other in tank pump. There are a LOT of high-output aftermarket pumps available, but the durability is more of a goal that more fuel volume. What are the pitfalls I should avoid?? Thanks for your help on this. Best to do it ONCE and the right way......

 

Get a FASS 90 gph and be done with it. Supposedly good for 50,000 hours...at 200K miles my truck has just over 7,000 hours on the meter...20 psi fuel pressure is moer than adequate....you will need the original in tank pick up assembly, but those aren't too hard to find.

Kurt

 

IIRC the 24 valves never had a mechanical pump in fact I believe there is no lobe on the cam to run a mechanical pump

 

Did some digging and I found a pic of the in-tank fuel pump module and a wiring harness with a relay in the kit. Under the truck, I finally found where they hid this relay and harness behind the driver's side front wheelwell. There was an orange wire that it connected to the wiring connector going back down the frame rail. Apparently, the stock wiring must have had a wire for an in-tank pump (maybe a gas application) and there was no wiring added at the tank. I also spotted where the Dealer that installed the pump broke off the drivers side crossmember bolts and WELDED the crossmember to the frame!!!! Thanks a LOT! I was considering cutting a hole in the bed floor and making a removable panel to get at the pump without dropping the tank, but it sits below a brace at the front of the box. Guess I will be cutting welds and drilling out bolts if I ever remove the tank. The newer fuel pump "modules" we see in all the gas cars and trucks in the shop have an interesting feature that It took me a while to figure out. They have a small venturi near the bottom that has a small jet or stream of fuel that when the pump is running, this effectively fills up the module well above the fuel level in the tank. This keeps low fuel levels from allowing the pump to suck air if the fuel sloshes around when cornering or braking. Pump rpm's go WAY up when this happens, and cannot help out pump life at all. Wonder if this helped kill the engine mounted lift pumps?? Years ago, we had a 95 Grand Prix towed in that showed fuel on the gauge, but actually ran out of gas. No pressure, so we put 5 gal of gas in it, and it ran well. One week later, it came in and the fuel pump had failed. I cut that old pump apart, and the brushes had melted to the plastic brush holder and the spring could not push it out to the commutator. I wonder if that could be why Dodge went to the in-tank module?? Definitely a good reason to keep never run your tank low..........