94-98 cummins lift pump upgrade ?'ss

[Swaggs]

Hey I went to cummins bridgeway, a parts/service place near me in michigan, ordered everything but the pump. got the gaskets, fuel line, seals, and spacer. for like 40 bucks or something, and ordered the lift pump with the old part number through dieselpartsdirect.com for $84 plus 14 shipping. I hope its the low pressure pump. we will see

[cumminz90]

Sounds sweet i havent got a chance to get to the local cummins dealer yeat but i hope thats what it costs me lol

[Swaggs]

hey, I ordered my piston pump yesterday from the site I listed above.. directdieselparts.com, i think. and it came in today. SUPER fast, pretty impressed. anyways, it has the purple dot on it, which someone said is a low-pressure pump. I am pretty happy that it was 98 dollars including shipping. the other stuff should be in at cummins tomorrow.. cant wait.. I wish I had a fuel pressure gauge to see what she is running now.

[1STGENFARMBOY]

you can get a machanical gauge from summit for like $15.00 and a threaded banjo bolt from genoes for
i think around $10.00 and leave it under the hood.
corse i have mine in the cab right now cause im skeert of my PSI droping to (0)

[cumminz90]

Sounds like i mite have to order one of the when you put the lift pumo on did it make any difference power, egt, or smoke wise jw?

[Swaggs]

Got the lift pump in. I didnt notice much difference in power, but thats probably because I need a bigger turbo, all my upgrades are on the fuel side, denny t fuel screw...etc.. It does seem to smoke a little more.. that denny t really lets the fuel in.. I am going to back out my full fuel screw a bit, and turn the starwheel up a few notches to try and clean her up.. I feel better knowing that my VE wont run out of fuel tho

[SChandler]

hey, I ordered my piston pump yesterday from the site I listed above.. directdieselparts.com, i think. and it came in today. SUPER fast, pretty impressed. anyways, it has the purple dot on it, which someone said is a low-pressure pump. I am pretty happy that it was 98 dollars including shipping. the other stuff should be in at cummins tomorrow.. cant wait.. I wish I had a fuel pressure gauge to see what she is running now.

Which brand is the pump you got? The factory ones were manufactured by Carter, iirc. The genuine Carter ones seem to be pretty expensive from Cummins and from Case ($200-$300). It seems to me that there is one of the non-Carter brand ones that only puts out single digit pressures instead of the 12-15 psi expected of the Carter pump.

[Swaggs]

well that would be an issue.. It is the same part number, and it has the purple dot that people have said is the correct pump.. I will have to put a gauge on it and we will see.. anyone else experience this?

[jhedge]

The piston lift pumps have been manufactured for Cummins by 4 or 5 companys over the years and Carter was probably the best (they were my favorite) but there probably isn't a whole lot of difference.

There is actually a family of pumps that were used on the B and C series in a bunch of different applications, some pumps were used on both engines and some were only used on one or the other but they all look basicly the same (this is why the B-Series engine gets a spacer between the block and the pump). There are around 7 pumps in the family and 4 of those are identified with a color coded dot, which will be either red, blue, green, or purple (Cummins called it "violet"). The dots moved around over the years, but they were always applied by the pump manufacturer and since Cummins paints the engine after it's assembled, you will only see the dot if you buy one as a replacement part (which are sold unpainted), if you pull it off another truck the paint dot trick doesn't work. I think some of the pumps did have the dot on the bottom of the primer boot, so those might show up after the engine was painted. All of the pumps have been revised over the years and received new part numbers 6 or 8 times.

One pump in the family of lift pumps flows a lot less fuel than the rest of the pumps, this is the one with the purple dot. At 800 RPM (That's 800 at the crank, 400 at the cam) it's flow profile looks like this:

d1.png

At 2200 RPM, it looks like this:

d2.png

It will actually put out more pressure then that, max should be around 15 psi.
Here are all of the part numbers of the purple dot pumps, in order (ie: each part number superceeded the part number listed above it):
3918076
3930349
3932228
3933256
3936320
4944714
4988751

Why so many part numbers? The earlier pumps were kind of noisy and some material changes were made to some of the seals in the later pumps to make them better compatable with ultra low sulfur diesel and biodiesel, and then some of the supplier change stuff...

The 2nd gen dodge that used the P-pump had the lift pump with the blue dot, which is the same as the green dot except for the outlet fitting.

[SChandler]

Wow, that's a lot of good info there jhedge. Thanks.

[PToombs]

Richie! Sticky that post!

[bmoeller]

If you got a 2nd gen pump, did you get the 2nd gen strainer too? The spacer actually replaces the strainer on an application where they use a remote strainer.

That strainer also has the fuel heater attached to it on the 2nd gen trucks.

[PToombs]

Yeah, throw that POS right away. More trouble than it's worth!