lift pump pressure

[dj]

After replacing my fuel lift pump, I installed a dirrect reading on the side of the injection pump to monitor the pressure. apresure at idle is 15psi, and at 2000rpm under moderate load 12psi. At times, whether cruising or at idle the pressure mwill vary by 1psi plus or minus. Does anyone know the causr of this variation? This can happen shortly after start-up or after total warm-up. Sometimes, itwill stop after 100 miles or so. Neither Cummins or the Dealer can explain it.











Stock 2001 Quad-cab 245hp- 6spd

 

[MD500E]

My new lift pump reads 11-12 at idle and drops to 6 under acceleration. My new spa digital gauge just went nuts yesterday and now reads 2-40 and all over the scale while driving. It will show 3 then 24 then 1 then 33 and so on. I am hoping it is just a bad sender. Its only a month old!

 

[roadranger]

Fuel Press. Gauge

I've got the electric Stewart Warner setup Steve St Laurent was promoing awhile back, set up like his.



For some reason, the gauge reads 15 psi idling or going down the road at 65 mph loaded. Very rarely will it show a drop to 12 psi while pulling a good hill. Hope this thing is reading OK!

OR I must have a really good pump.



Also, when I start 'er up, while waiting for the wait lite to go out, the fuel pressure will jump up to 15 psi, then drop down to 2 psi before the wait lite goes out. When I turn the key to crank 'er over, it fires up right away, and press is back up to 15 psi.



Hope this is normal.

 

[LSMITH]

Krussel, more than likely what you have is a bad connection where the DIN connector mounts to the sender. Take the DIN (square plug connector) off and bend the three blades out just slightly. Apply some dielectric grease to the face of the DIN connector and re-install it. I think your problems will stop.



Roadranger, the pressures you list seem a hair high. I would hook up a temporary mechanical guage to the oulet from the filter and go for a ride. More than likely you will see the same readings as your full time guage and have a good strong lift pump, but to be sure I would verify that the readings are correct.



Thinking more about this you could also have a return check valve that is a tad strong for relief pressure. It is in the return line banjo fitting. You can check it to see what pressure it is relieving at by taking it off and hooking up a regulated air supply to it. From what I have read it should start relieving at about 10 PSI and be fully open by 15 PSI. Credit to Evan Beck (I think) for the relief info. If I have it screwed up please correct me.

 

[jman]

I have been wondering if I should throw a new lift pump at mine. I show about 13 psi at idle and 5-9 cruising on flat land, but as soon as I start up a hill at 70 mph it drops to 0 psi in a hurry and stays there until the boost goes down. I only have 17,000 miles and can get it changed under warranty, but don't know how low is low enough for warranty.



If anyone has any advise I would appreciated it.



jman

 

[BigDaddy]

The 2000 FSM states, minimum pressure: 10 psi pre-filter and a maximum differential pressure of 5 psi @ idle.



jman,



With this in mind, I don't think the dealer will warranty your pump. Unfortunately, the FSM does not specify any spec. 's at WOT

 

[LSMITH]

jman, change the lift pump!!! If you have to pay so be it, it needs a fresh one.

 

[Bigsaint]

krussell, I agree with LSmith, check the connection at the SPA elbow, which plugs into the sender. You might want to also pull the SPA elbow apart and check the connections inside, you'll see that they are not connected by much surface area and other members have had problems in this area as well. If you remove the screw from the top of the elbow and then push down on the center piece, the plastic fitting will pop right out, revealing the connections.



If you have the sender at the inlet to the VP44, move it below the fuel filter canister.



Scott W.

 

[jman]

I have my sender located at the VP44 inlet also. Is it better to move it to the bottom of the filter housing? And if so can it be mounted right there or does it need to be remote mounted. My earlier post states my pressures and I don't think they sound to good no matter where I'm getting readings from, but if I'm going to change the pump I might as well move the sender while I'm there.



If anyone knows the part # for the lift pumps off the top of their head I would appreciate it so I can swing by Cummins Rocky Mountain sometime this week.

 

[Whitmore]

jman, just bought the CUMMINS lift pump last week #3990105 for $142. 66.

The install was easy , I put it in the stock location for now while I evaluate the whole deal, Do I move the pump back or add another pump at the tank, still thinking ... ... ... ... . Kevin

 

[Bigsaint]

jman, I would either move it or isolate it with a snubber line, there's quite a bit of turblence at the inlet head and the pulses won't do much for the life of the sender. That being said, I've had my SPA FP sender at two locations, both without a snubber. I started off at the inlet to the fuel filter canister and moved it below to the bottom of the fuel filter canister when I upgraded my lines. The sender is still going strong, but I'd more concerned with the Westach sender as there as been more than a few failures with that gauge.



Scott W.

 

[jman]

OK, now I have the part #, any advice on changing this silly thing. I know I have read hundred of posts on this, but for a first time lift pump changer would you do it from the top or crawl underneath the beast.

 

[Big Don]

Guys,



I am at wits end with my lift pump. I get 3-5 psi at WOT sitting still. I am getting ready to bomb this thing majorly and am worried about my lift pump. The dealer checked it and they say as long as it puts out 10 psi + at idle then I am fine. They do not care about WOT and say I should not worry, what do yall think??

If I want to purchase my own lift pump, what part # should I buy. I have a 2000 model with the 235 hp engine and the 6 speed.



thanks

Don

 

[SEmerson]

wot is what counts. I gave up on stock lift pumps and went malley on the frame. I just keep my stock pump for emergancys.

 

[Bigsaint]

Don, you have to replace that pump if you are seeing 3-5 psi's while not under a load, no way would I add any fueling BOMB's with that kinda FP. You have a few choices... if the dealer won't replace the pump under warranty you could by the latest and greatest from Cummins and put it right back in the same place as the existing Carter pump, guessing that the warranty would still be intact. Your next option would be to relocate the Carter pump back by the fuel tank, I don't know what this would do to the warranty, again, if you are concerned. More than a few members have added the pusher pump to aid the front lift pump and help prolong it's life. Personally, I only want one lift pump.



The Mallory is not flawless. My first Mallory 4150 went out after only a few months of service. The second Mallory is still doing well, with about 8 months of service. It provides more than enough fuel for what I need (see the sig. below). The question is longetivity.



The dealer's statement may be true for a stock CTD, you will need more fuel for those stage 2 injectors. A standstill check of fuel pressure does not prove much,see what you have at WOT while under max. boost to get the real numbers.



Also, you don't need to see 20 psi's of FP at idle for a BOMBed truck. My Mallory is set for 12 psi's (post filter), which I can drag down to about 6-8 at WOT. Set up the truck right before the fueling additions and you and the truck will be happy with the mods.



Scott W.

 

[RADdodge]

There has been a tremendous amount of info on lift pumps over the past year. Last summer, I decided to add some insurance to my trips by adding an auxiliary fuel pump just ahead of the fuel tank. (I also bought a spare lift pump to carry along just in case) Rather that adding a circuit for the Carter pump, I decided to use the starter relay, that way when the starter is engaged, the pump is off, otherwise current runs to the pump. Also I added a fuel filter ahead of the pump along with a check valve. The check valve will allow fuel to flow to the primary lift pump if the auxiliary pump (I have it hooked up to a switch for utility purposes) should fail. The primary lift pump sucks the fuel from aft fuel filter very well, in fact I could not really detect any loss of pressure. With the aft Carter pump energized, fuel pressure at the inlet of the injector pump is about 20 psi, 12 - 14 at WOT. Anyway, I wanted to share the idea of the check valve. I also feel that an auxiliary fuel filter (30 micron) is a good investment. You can order the Racor fuel filter with a heater and water in fuel sensor. Racor also makes a cool gauge that gives an audible alarm as well as a visual indication of either water in fuel or a plugged fuel filter. I also installed a shut off valve ahead of the fuel filter for changing filter elements. The Carter pump is isolated to reduce noise ( I can't hear it and I have good hearing). Here's a picture

 

[jman]

RADdodge, that is a very impressive looking setup!! I'm impressed!

 

[Ramafid]

I'll second that! My setup looks almost the same but I don't have that trick fuel filter and bypass line. I'm green with envy!

 

[B. Gill]

RADdodge

, very nice setup indeed

what is the sending unit type sensor on the filter for ?

thanks

bob

 

[Big Don]

Guys,

How can I convince my dealer to replace my lift pump. With everything still stock on it except gages and PE EZ my pressure is 10-11 at idle, but sitting still, no load at 3000 rpm's pressure drops to 3-4 psi. I have parts ready to bomb: DD II's, Jardine 4" no muffler exhaust system, K&N filter and 14 cm turbine housing. I am afraid to bomb yet until I get the lift pump fixed. I also want a good fuel pressure gage setup to go in the cab. I'd like to have one of those column mounts with a fuel pressure gage abd a sending unit to put pre filter or post filter, not sure where to put it. I asume post filter would be best. Any help would be useful.

On a side note I see many abbreviations for upgraded fueling boxes like the TTPM and DDTT. I am familiar with the TST powermax and Van AAken, Power edge boxes, but do not know what these other units are any help with explanations would be great. I am a die hard FIRST GEN man, and the more I fool with the second gen trucks with all their little computer quirks the less I like them. Not slamming anyone, but I like the old trucks when you just turn the pumps up add different injectors and get power out of them.



later

Don