Lift Pump ?

[R C Cola]

Did a search and not finding. Decided that 590k on the lift pump is probably enough. Ordered from parts store and got what looks to me like a piston pump, looking at invoice it says application 94 Ram 2500, 5. 9 dsl /ATF #73104 Mfg. is Airtex out of ILL. Upon inspection it looks like what I might call a piston pump. 2 Ports only on this (in & out) w/primer. My Question " Can I use this on my 91 or is it totally wrong ? " R C

 

[PToombs]

RC, yes and no. You can use it, but you need the line from the pump to the filter head, 2 spacer plates, and you need to grind the insulation off the tappet cover in 1 spot. There are part #'s in the stickies for the rest of the parts. Or I could go dig out my receipt and get them.

It's easier to replace with the stock one. If you have much for performance mods, the piston pump is better.

 

[Paychk]

I was under the impression that there are two different piston lift pumps; one that matches the VE pumps input pressure requirements and the other that goes to the Inline injector pump... 94 was the starting year for the inline.

 

[PToombs]

Hi pressure and low pressure. Low is 15 psi and is the preferred one. That's the one listed in the stickie. I think the high pressure one is from the 8. 3's, but don't quote me on that!

 

[Bob Beauchaine]

You've got the high pressure lift pump - too much psi for our VEs. Check the stickies for a pressure reducer to cut the psi down to 15 psi. The one you've got puts out about 50 psi. Carter built the pumps and has a rebuild kit with a softer spring in it. I can get you the p/n's for the spacer, gaskets and plumbing if you can't find the numbers with a search.



Bob

 

[PToombs]

Here are the part numbers,



Cummins Part # 3936320 lift pump (qty 1)

# 3914753 Fuel Line (qty 1)

# 3931348 Gasket (qty 2)

# 3914284 Spacer (qty1)

# 3918191 Seals (qty 2)



The seals are for the banjo fitting on the filter head.



The high pressure one has a larger piston and 2 springs in it. On 1st gen there are comparison pics.

 

[Tippin Spotted Cow]

My power hungry ego now wonders what 50psi of fuel pressure would do for power..... And also for all the seals and such on the VE.

 

[JLEONARD]

 And also for all the seals and such on the VE

You may "undercoat" your truck with #2.....

Paint is cheaper.

 

[Tippin Spotted Cow]

I'll bet for about 5 seconds I'd have the fastest truck on the block, though.



Seriously, how high can you run your fuel pressure on a cranked up VE before youre pushing more to it than it can push through to the motor? Is there any way to modify the afformentioned pump to push at say 20-25psi, and what would that do for your VE if it did?

 

[JLEONARD]

You don't want a lot of fuel pressure... you want fuel volume. Those are two different characteristics.

If it were me, I'd go up a little in line size from the tank to the pump ... use a 10 to 15 psi pump (a regulator unecessarily complicates the system) that supplies a min of 10 gal per hour at a min of 7 psi continuously. You can buy electrics that will do that... and I'm sure mechanicals.

Pete... any idea what the flow specs are for the piston pump you mentioned?

 

[PToombs]

Jay, I don't have a clue. I was going to look in the service books at work to see if I could find anything, but we got busy.

I hate it when work gets in the way of my hobbies!



Matt, you can run about 30 psi before the seal gets spectacularly blown out. Usually they will leak at less pressure, but 30 is the known fail point of a good (newish) seal.



Alot of guys are running a boost referenced regulator on a very large pump. With huge injectors. Then when you need high volume on a WOT run, you get it. Then when you are done, the pressure and volume drops back down.

 

[R C Cola]

Fuel Pump

Sounds like a mod I will want to do later when more bucks available. Thanks