NEW Lift Pump a "Performance" item??????!!!!!!!

[larryq]

Vaugn.
Now I wished I had looked that new pump over better than I did... .
I didn't notice any other markings...
as far as the connector. . it consisted of a 2 pin connector that matched the harness on the truck. . but where it went into the pump appeared to be "Screw Down" terminals.

I. E. you could remove the connector and put whatever one you wanted on...

I may be wrong. . and now that it's installed I'll never be able to get a good look at it...
Maybe if someone else has the new part number pump in their hand.....

. HEY VAMAN!!!!!!!!!!!!CHECK IT OUT FOR US!!!!!!

One other thing I've noticed with this new pump... ...
QUIET!!!!!!!
My old pump sounded like a sewing machine (that's how I knew it was still working... #ad
)

Since this pump is a NEW part number... and not just a revision... (I. E. 123456 becomes 123456A) It may indeed be the same pump you see in summit.

If it is indeed "Screw Down" terminals... well just reuse the connector off the old pump. . no soldering required!

As far a "Mods"
I would NEVER do anything to void my warranty!
If God... . oh. . sorry. . I mean DODGE. . had meant me to have "More Power"...
Then they would have GIVEN IT TO ME WHEN I BOUGHT THE TRUCK NEW.

#ad


Larry

 

[WyoJim]

I have been carrying this pump under the seat as a spare but maybe i had better put it on.
I don't have a pressure guage. If Vaman's perks his up I probably will.

Anyhow I just went out and looked at it and the two terminals are rivits. Its #3938435 on my receipt and on the box, but the pump has a different number 85316?. I can't see very good at night.

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98. 5 24 valve auto, QC, LB, EZ, DTT vb 9 1/2ft 3500# slide in S&S Camper

 

[MikeR]

I recently installed the 3938435 pump. Everything was the same in appearance except for the wire connector. The old pump had the connector in the pump base,but the new pump had about a 5" pigtail with a factory style connector on the end. That's the only diifference I saw. I even took the new one and old one apart to look at the vanes... they were the same.

-Mike

 

[Mopar-muscle]

all this talk about pressure ... looks like i wasted alot of time testing and giving you guys the info ... pressure is a restriction to flow , as long as you have a couple psi at WOT , you have more than enough fuel . go to the pumps,lines and what not thread and read it again , there is some very interesting data there .

 

[Vaman]

Installed the new pump and I'm afraid I don't have much to offer you guys. I'm pretty frustrated for a few reasons. For starters, only one of the three nuts for the lift pump would come off properly. There was so much red loctite on the threads that the all thread started unscrewing from the pump itself and I didn't see it. Quick tip... disconnect your fuel lines completely because if you don't, you'll end up using the all thread in the pump as a jacking screw and stressing the fuel lines (this might be different for later models). Anyhow, the piece of crap (I think) autometer fuel gauge has to be wrong because with a new filter and new lift pump, I'm reading 2 pounds now instead of 1 (no change in performance). I can't find a gauge around here in that range to double check it with. The gauge I tried to use has too high of a range to tell what's going on with any accuracy. As far as the pressure comment let me first say this... I was a Reactor Operator, Instructor, and Maintenance Technician in the nuclear power field for 17 years. I have a strong background in fluid thermodynamics, heat transfer, instrumentation, a little metallurgy, and electronics. The pressure/flow relationship can be hard to discuss because so many variables have to be taken into account. Mopar, I appreciate very much all the work you guys are doing but I can't agree with the statement of "pressure is a restriction to flow". It depends on where you're reading the pressure. Using that logic in it's purest form, if I turn my lift pump off (no pressure), I'll have max flow. Your statement only holds true for one condition... that's when there is a restriction in the system downstream of your monitoring point (pressure upstream will increase and flow will decrease). In a system with set physical characteristics, an increase in the pressure source will result in an increase in both overall system pressure and system flow. But, if you keep the same pressure source, introduce a restriction into the system, system flow will decrease, pressure pre-restriction will increase, and pressure post-restriction will decrease (your statement condition). With all things being held constant in our fuel systems, a higher pressure would generally indicate more favorable conditions (not to exceed any design specs for the injection pump input pressure). The tech manual gives minimum pressure specifications (10 psig pre filter and a 5 psig max filter drop) and if you don't meet these, you replace the pressure source (lift pump). This is based on the assumption that the fuel system is unchanged and the only variable is the condition of the lift pump. In Larry's case, a higher pressure (again, with the rest of the fuel system unchanged), obviously made a big difference in performance for the better. You have to look at basically three things when you discuss this stuff... the restrictions (or headloss in the system), the monitoring points, and the pressure source. Here's the wrap up... everything that everyone is doing is designed to increase pressure and flow at the injection pump suction. Webers, banjos, and new lines decrease headloss and INCREASE downstream pressure. New lift pumps provide a higher source pressure and therefore INCREASE overall system pressure and flow. I'm done... Flame away.

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98. 5 2500, 24v, 5 speed, QC, 4x4, 4. 10 LSD, short bed, Line-X liner, tow package, camper suspension, Westin nerfs, camper shell, TST PowerMax Competition, 275 RVs, Psychotty air, HX-40, 4" straight pipe exhaust, ProComp A/T 305/70/R16s, EGT/Boost/Fuel pressure pillar gauges, Grover air horns... Love my Cummins, no love for Dodge

 

[Mopar-muscle]

no flames , but you know i was not talking about an engine not running .

as far as the pressure vs. flow issue , you know more than me and i'm not going to even try to one up you , but with a flow meter in the return line and varying pressure right at the inlet to the VP44 as the pressure went down the flow back to the tank increased , till it reached its maximum and would go no higher and the pressure began to rise again , that is where my pressure is a restriction to flow comes from , we went from 0 psi to 3-4 psi and the flow number was the same .

not trying to take away from larry , when my lift pump was replaced the first time my performance also increased , but the latest testing , no performance increase with a change from 0psi to a high of 6 psi .

edited for spelling

[This message has been edited by Mopar-muscle (edited 05-13-2001). ]

 

[David_VT]

Larry,
You must have parked the truck too close to a phone line. I got an email from my orphan.

It said:

"Please take me back, this guy is killing me with too much WOT... pant... pant... help... . "

Geez Larry, what are you doing to that poor thing?

 

[larryq]

Dave... . I thought all those calls were to 1-900 numbers... . At least that I could understand!!

If that thing is crying then its' time to take it back to "Boot Camp" and toughen it up a bit.

ARRGGGGHHHHHH "Thank you sir... may I have another?!?!?!?!"... .

#ad


Vaman...
I'm sorry to hear your situation hasn't improved... .

Makes me wonder.....

Just to give you a differant look at this. .
My wife took the truck this AM to go shopping.

When she got home... she asked me straight. . what I did to the truck!...

In my situation. . I must have had a pump that was so far gone that it was reducing flow.

as I said in the beginning... . I hope my injection pump is ok... .
I must have been running without proper "Flow/Pressure" for a while!!!

 

[PAYCHECK]

Venturi? also remember along with all the other variables(such as head etc. ) the type of fluid that is being moved also affects the numbers!

------------------
01 2500HD QC,SB,3. 54,5 spd,4X4,241HD,SLT+,Sport all black,fully loaded,all leather htd,jacobs e-brake,tow pack,camper pack,,full rhino lining bed and rocker panels,265/75r16 BFG ATs ko,nerf bars,everthing black,4'' Jardine,A. M. Pro Comp pyro & boost on a-pillar,EZ,NO stickers except cummins on door,License plate-1 CUMN, NRA endowment life member

 

[Ladders]

YES, IT IS A Performance item!

Had mine changed today, 8-10 @ idle, 0-2 @ WOT before.



DC # on box: 1-05015723AB next line: 73831 12/20/00



Know this is NOT the pump talked about above (3938435) BUT the readings are: 15-17 at idle, 8 @ WOT about 5 before @ 65-70 cruising and now 10. Boost seems to build quicker, due to more fuel?



Dont expect this one to last as it being a revision and build date last DEC(?) or packing date(?), but its better than the old one.



Just an update (didnt get to see the pump before it was installed).



By the way, the OM calls for packing of 2x4 front wheel bearings @ 60k and was gonna have the dealer do em but they are SEALED units... another DC error in service (thank G. O. D. ). So if you have a y2k you may want to double ck if yours are sealed.



SOTSU!! runs agn!!



\\BF//



PS: waiting for parts for the oil leak (tech says most are from the cam plug, that he's worked on) and trans shifting problem. Reported a low power problem (per tech) and we now suspect the valves need adjusting. I plan to have the flywheel sent in to have it bored to a bigger pilot bearing (approx 150-180$ - out of my pocket - but I feel its worth it since it will be removed to fix the oil leak anyhows). Will post results next month (scheduled for EOM work - before 30th - hopefully).





EDIT to answer ques below: too soon to tell, the go pedal is down to the block too much yet. Give me a week or 2 to cool the eng down and get back to "normal" driving



So, Steve, i'm one revision behind on avail pumps but 2 behind on latest... ... . HMMMMMMMMM

 

[Michael Hughes]

I would like to know what you guys fuel milage was before and after the lift pump change?

 

[Steve St.Laurent]

The current latest rev pump has an AC after it on the DC part number. There is yet ANOTHER new rev lift pump coming out soon but it isn't available as of yet, the new one is supposed to have hardened seats. Cummins has it listed already but is listed as status 80 - which means it can't be ordered yet.



-Steve

 

[Steven]

New pump MPG

For those of you who noticed big changes with the new pump ... was there a decrease in your MPG?

 

[Ladders]

Fuel miles

Steven,

to answer your ques, no I saw an increase this weekend on the "normal" long trip. About 2-3 miles BUTT I think the wind was NOT a factor this time (usually a headwind to fight). As stated before not sure till I get more miles on it. The computer showed an increase over the normal route and it just might have been lower wind factor. But a gud answer is, no I am not seeing a lower mpg due to the replacement - probably be the same after I adjust to the go pedal.



SOTSU!!

\\BF//

 

[dresslered]

Please post latest lift pump P/N when available

Steve St. Laurent-

Please keep us posted with your findings. You seem to be the forerunner in this area. I'm at 23,000-miles and getting the following readings:



idle: 11-psi

normal driving: 6 to 9-psi

mashed through the floorboard: 2 to 3-psi temporarily



I'm thinking of relocating back toward the tank but might want to have the dealer put in the latest lift pump when available. If you find out this part number, please let us know!!! Thanks.

 

[Bigsaint]

I'm thinking of relocating back toward the tank but might want to have the dealer put in the latest lift pump when available. If you find out this part number, please let us know!!! Thanks.

Ahhh, c'mon in David. Really, the water is FINE



Scott W.

 

[dresslered]

Careful now Scott! I already have to resist HVAC and his box of magic tonight at the Ramrunner's!

 

[Benson]

This all sounds pretty interesting. I have been busy (and busy procrastinating). I have some catching up to do. I missed May Madness, when's the next little get together so I can see these things in person? I have several "ad ons" sitting out in the garage waiting for me to get with it.

 

[JTBMC]

I recently purchased a new lift pump from Cummins in New Orleans, asked for # 3938435 and was handed #3990105 with pig tail #4025182 with manufacture date of May 2001. Parts man said it was an updated item. I'm waiting on my new Banjo Bolts from Ray Torresdal before I do the install.

Preasures fom old pump

Idle Pre 13

idle post 10

WOT 5

I will advise new preasures as soon as new Bombs arrive.