Ive read alot of information on forums about the lift pump issues on these trucks. The one that draws my attenion the most is on Morpar's web sight. In my mind in all there theorys there missing one important aspect. There comparing flow/ pressure and then trying to justify there theory with gpm pump flow figures.The gpm that are stated on these pumps are free flowing figures, with no suction load and no head pressure at all! What any pump will flow is soly dependend on no restrictions. Why? Becouse the power source driving the pump is not static. It's a motor torque issue. You can have a aftermarket lift pump with more motor torque, but when you restrict the flow, thanks to the overflow valve then the pressure rises. So you say so what? So I say, all the figureing on this 70% return to tank based on gpm flow from pump is nonsense. The pump stalls to a extent till the pressure relief valve starts to open. Up to that point you have very little increase in flow just becouse the pressure has increased.

 

Yeah, this was beaten to death a while back.

The vp provides the pressure at the injector, the flow is there to provide volume of fuel on hand when needed.

I agree that overpressure with a blow off valve is kinda pointless, unless you need a pressure number, but the gauges for our trucks read pressure, not flow. I think it is used as a direct correlation to be sure you are getting fuel delivered and not pulling on it.

 

I would like to talk about it with you.If you want to Im not trying to tell anybody anything! Really just wandering about us stock guys and all this high output pump thing. I understand there has to be enough flow to fill the (lets call it the bowl) in the v/p it looks to me like Bosch thought 6# min 10# sufficient. Know if you want to talk about cooling flow just more head pressure at the v/p to fill the bowl should't make more flow out of overflow valve. I know this is a touchy subject with the aftermarket croud. But with us guys not messing with the h/p mods I think there might be some gray area on these wildly expensive aftermarket pumps and all the problems they can cause for us old gramps just trying to keep our old rigs running till we die

 

I know what you mean, I'm from the old school carburetion/cubic inches crowd so when I started messing with new stuff I had to play catch up. I understand it I just can't explain it real well!!

Katoom knows what's up and so does infidel with this stuff, and are good at explanation.

I agree though that the vp needs plenty of reserve to draw from and the stock fuel lines are marginal. I would like to upgrade to 1/2" lines when I do the FASS on my truck, just haven't had the funds to do it all at once. That will get me plenty of pressure and flow for RV275's and and Edge Easy, which is all I really need for towing duty and mileage gains. I have already done the clutch and exhaust, the rest of the truck is stout enough.

And, this site is for discussions, and is pretty good for that, Nobody really tolerates anyone flaming or condescending to others and is good at making sure that is known.

 

The dealers flow vs pressure is a curve ball!
If the system is not changed after the lift pump pressure is proportional to flow.
If the LP puts out x pressure vs y pressure there will be a difference in flow.

Fact is the stock LP is junk before you install it.
They fail in many ways and at any time. Some even fail but sound like they are still working.
Mounting anything electrical on a shaking motor is wrong anyway you look at it. ( ECM is electronic) There is a difference.
mounting an electric pump so it has to draw from a tank is wrong too. They are designed to PUSH fuel.
This system is a DODGE issue not Cummins. Dodge furnishes the LP.
I suggest using something like an Areomotive pump or even a Holley if you use the gearotor one. Set the pressure to 12-15 and it will run a long time.
I had an Areomotive on my 02 for 7-8 years and never had an issue with it.

 

Yes sir I understand what your trying to say. I know that the right way to transfer fuel is to get that pump submerged in the tank. I'm sure the only problem with this system is the fact that the fuel comming through the retail system is getting so contaminated that it just eats that pump up over time. I'm not a new commer to these trucks I have some views on all the systems to transfer fuel and would love to disscusse them with someone I haven't used all of them so I'm making educated assumpions like all of us are doing could use some help.