Engine/Transmission (1998.5 - 2002) Old lift pump vs in-tank lift pump

[FLynes]

I was talking with the tech at S&S Dodge yesterday and was telling him about how I was thinking of putting in a FASS, so I could maintain pressure to the VP44. He started laughing and told me that I shouldn't be worried about pressure, so much as volume. He then told me that, when they have trucks in with lift pump problems on the 24V engines, the first thing they do is a volume test, not a pressure test. I told him about how some of the guys here have the Mopar in-tank pump and are unhappy with the low pressure. He responded with, "Well, once the line is pressurized, who cares how much pressure is there, as long as the VP44 is getting volume, and the new in-tank pump delivers volume, besides the fact that it's pushing the fuel, not pulling it".



The more he talked, the more he started making sense, which kinda scares me a little. Does he have a valid point?

 

[16919]

They both suck. . get a FASS, Air dog, Rasp, Glacier, or the likes. The vp 44 must have at least 5psi to fully fill the pump. That is what BOSCH says; they made the pump, not dodge. I would go with what they said. Do some reading around on here about oem lift pumps. You will run away from the dealers advice after reading.

 

[DCreed]

ditto w/James much happier and less worries W/fass &filter unit

 

[Huff N Puff]

Ive had this argument many times before,so here we go again

First, the dodge tech is right. You cannot move enough fuel thru the 1/4in. fitting in the fuel module,because atmospheric pressure is ALL that is pushing the fuel to your pump out side the tank. So you turn your 100 or your 90 GPH pump into a 30GPH pump by drawing thru a 1/4in fitting. That is the effective area of the fitting in the old fuel module.

 

[FourBarR]

I still have the oem pump back by the tank. would not install the in tank one,mainly because if it quits you get towed and get the tank removed to change it. I can change mine on the side of the road in 15 minutes. just carry a spare pump. works for me.

 

[jeepit]

My intank is comimg out in a couple weeks..... AirDog going in.

 

[blacksheepdiesel]

The Dodge tech is a parrot, simply repeating what he is told to say.

The fact is that the electric pump should have never been placed on the engine to start with which caused way too many people way too many problems. The in-tank pump is a better idea but they put too small a pump in there for the job. The best fix is AirDog or the like. My AirDog has been on for 2 years and 140,000 miles; zero issues. AND my AirDog is mounted IN the bed of the truck on drivers side so it has to suck fuel from 2 feet below it. Still has 19psi at idle and full throttle. Also, the AirDog was engineered to work with the factory suction tube without modification and does so on highly fueled trucks. I highly recommend AirDog. PM me for dealer contact.

Godspeed,
Trent

 

[JMetzger]

Dodge talks about the in tank pump being so great. I put a calibrated electronic Vac/pressure gauge on two trucks (01 & 02) And under a full load one had a travel trailer the other was a 5er and at WOT one pulled 1in Vac & the other pulled 3in Vac. Now tell me that is good for the VP. Just a thought as how DC doesn't care about it's customers.

 

[FLynes]

So it would seem that the general consensus here is that pressure does matter. Christ, if I'd known I was going to poke a hornet's nest with this one... . :--)

 

[Fishin Guide]

Dodge talks about the in tank pump being so great. I put a calibrated electronic Vac/pressure gauge on two trucks (01 & 02) And under a full load one had a travel trailer the other was a 5er and at WOT one pulled 1in Vac & the other pulled 3in Vac. Now tell me that is good for the VP. Just a thought as how DC doesn't care about it's customers.

I agree completely!



I found out what vacuum can do when I installed my 12V mechanical lift pump. Just by installing the Vulcan Draw Straw and -8 suction line, I increased my WOT pressures from 22psi to 37psi with no other changes.



I could bury a vacuum gauge before that mod!



Dave

 

[NoSeeUm]

Ask him to put something in writing that will "gaihr ruun tee" your VP44 for another 100k.



Jim

 

[Melton]

Can anyone tell me anything about the BD lift pumps

 

[rweis]

I am pretty sure the Bosch test stand fuel pressure value to calibrate the VP44 is a CONSTANT 13. 5 psi, I do not know the volume though.



FWIW



Bob Weis

 

[Fishin Guide]

I am pretty sure the Bosch test stand fuel pressure value to calibrate the VP44 is a CONSTANT 13. 5 psi, I do not know the volume though.



FWIW



Bob Weis

I agree. I would think the Bosch engineers would use a constant pressure. Which also means flow rate would vary depending on engine demands.



To me, volume is irrelevant if there is not enough pressure behind it. But that's just me.



Dave

 

[FLynes]

Trent, Just talked to Matt... . I'll be heading his way next month, on my way to Arizona, and hopefully he can schedule me in to do this AirDog. Thanks again for the info.

 

[blacksheepdiesel]

Fred,

Hey, that's good to hear! Have fun in Arizona.

Godspeed
Trent

 

[rweis]

Fishin Guide -



Exactely what the Gen 1 mechanical pump does, more rpm, more fuel;



Exactely what the RASP does, more rpm, more fuel;



I wonder why DC / Cummins ever changed the cam operated mechanical pump? For Gen 2 just leave it alone and put a bypass regulator on it. How could that not have been better than all the fuel failures since?



Probably in the end, the cam with pump lobe & pump IS the ultimate answer.



FASS, RASP, AIRDOG, WALBRO, CARTER, feeder pumps, twin pumps, frame pumps, gross overkill pumps, ... ... ... All because it is an involved job to change cam shafts and the average home "mechanic (including me)" can not do it in the driveway. IF we could, we would.



Bob Weis

 

[Fishin Guide]

Actually Bob, I bet you could do it just fine!



Everyone makes a cam swap out to be a black art. But believe me, if I can do it, anyone can!



There's no real special tools required for he home mechanic. Other than pressing the cam gears and I just pay the $7 to get it done.



There's some good fixes out there. But it is comforting to know I can get a pump at any parts house that has Cummins parts!



Dave

 

[Huff N Puff]

The Dodge tech is a parrot, simply repeating what he is told to say.



The fact is that the electric pump should have never been placed on the engine to start with which caused way too many people way too many problems. The in-tank pump is a better idea but they put too small a pump in there for the job. The best fix is AirDog or the like. My AirDog has been on for 2 years and 140,000 miles; zero issues. AND my AirDog is mounted IN the bed of the truck on drivers side so it has to suck fuel from 2 feet below it. Still has 19psi at idle and full throttle. Also, the AirDog was engineered to work with the factory suction tube without modification and does so on highly fueled trucks. I highly recommend AirDog. PM me for dealer contact.



Godspeed,

Trent

Not a very good idea to supply the fuel to a "highly fueled trucks" with a stock fuel module. Mopar reengineered the whole fuel system cause the fuel module was the problem. More so than the pump. So why would you leave it in?

 

[rweis]

Fishin Guide - ~ what did the cam solution $$ all totaled? Probably not much more than the "other" solutions.



Bob Weis