'00 Lift pump testing

[Big Don]

Guys,



Big Don here again. Just changed the fuel filter on my truck. It has 33,000 on it and the previous owner did not know to change it. He said the dealer told him to bring it in at 40,000 and they would change it.

Anyway, I changed the filter and checked the pressure at the schrader valve on the side of the injection pump (post filter check). It shows 10-12psi at idle and when I rev it up to 3,000 rpm's and hold it, pressure drops to 3-6psi. The only mods to the truck are a Power Edge EZ and a K&N filter.

I need some advice as to whether the pump is okay or if I need to take it to the dealer.



I am preparing to bomb and want to get everything right before I start. Don't need any hassles with warranty.



I am wanting to get a sending unit and a gage to put on the schrader valve. I think I can get some tubing and plumb it up to mount the sending unit on top of the engine somewhere then run wires into the cab to monitor fuel pressure as I am running up the road. Any suggestions would be appreciated.



thanks

Don

 

[LSMITH]

3-6 sounds awfully low with no load on the engine Don. If you can you should drive it with your tester on and see what the FP goes down to under load, my guess it is zero or nearly so. If is is zero to 3 PSI you are going to need a lift pump ASAP. Hope this helps.

 

[Bigsaint]

I agree with LSmith. If you are seeing 3-6 at 3000 rpms while at a standstill, your FP readings will be considerably less when under a load. If you can't rig the gauge for a test ride, plan on a new pump. I can only drop my psi's by 1 while stopped with 3000 rpms, while driving under a load it's a different story.



Scott W.

 

[Little Bill]

Big Don,



Pressure readings taken at the injector pump tap are notoriously erratic due to the hydraulic pulsations of the I/P intake. You'll get a more reliable measure if you take the readings at the fuel filter exit.

 

[cullyguy]

Go to Geno's Garage & buy one of Ray's tapped banjo bolts, install on bottom of fuel filter housing Remote mount the sender with fuel line up on the fire wall. This will protect the sender and post filter pressure readings will tell if you have any restriction. This assumes you make note of the readings when you put in a fresh filter. Oh yea, it sounds like lift pump time. If the dealer won't do it, go to Cummins & buy it- Save yourself some $$

 

[Big Don]

Guys,



To clarify, I was taking readings at the banjo fitting on the side of the high pressure pump (post filter). At idle pressure was @10-11 psi and at 3000 (no load) it dropped very low on the gage guessing @4psi. I called the Dodge dealer and they are looking at it at 2:00 today. They say they have a pump in stock. So..... we'll see. Are there any documents on the internet, that explain proper checking procedures or gage readings that are acceptable/nonacceptable?? I would like to have some documentation in hand when I walk in if possible.



thanks for all your help, yall are great!!!

 

[24V-DSL]

Check the PN....

Don... .



As you know, there have been numerous revisions to the lift pump. The back-up pump I bought from Cummins a few months ago is PN 3990105. This was a 5-1 revision, so don't know if there has been one since, but no point in having them replace with an outdated version. Might want to check.

 

[MikeR]

Yes your pump is bad. The Dodge shop manaul has psi outlines for what's good and bad. If memory serves, no less than 5psi at WOT is accepable in the book.



-Mike

 

[fj40charles]

Yep, the lift pump is bad. I had 14-16 PSI on my lift pump after I installed a fuel pressure gauge. Gradually over the last 8 months I noticed it was showing less and less pressure at idle. I had 12 PSI at idle for a about a month or so and on 12/23/01 I noticed the wild fluctuations on the gauge while driving on the highway. I knew it was time to replace the pump and luckily I had one in the back seat since I've been carrying this thing around as a spare just in case.



If you're seeing less than 14-16 PSI at idle, I think you're pump is in the process of degrading. .



Now, I've got to get on the pusher pump thing... .



Charles

 

[RJOL]

Just out of curiousity, what brand gauge did you install, and did you mount the sender directly to the VP44 or fuel filter? I have a Westach gauge, and when I initially mouted it directly to the VP44 the reading became erradic until I remounted the sender remotely away from the pump using fuel hose. Also, I don't think your pump is going out if you seeing 14-16 psi at idle. That's pretty standard, and even higher then most, for a 24V...

 

[Big Don]

Guys,

Just returned from the dealer. Their guys looked at it and checked the pressure with me watching. They did not understand why I expected the pump to maintain pressure at 3,000rpm's. Anyway, I did not have a leg to stand on without documenteation so I thanked them and left. He showed me in his manual that nowhere does it give a spec for maintaining pressure at anyspeed other than idle. His book calls for a minimum of 10psi prefilte while idling and postfilter should be no more than 5psi less than prefilter (if so, change filter). Mine checked @10-11 prefilter and 9-10 post filter at idle. He assured me I had no problems and that if she did lay down they would gladly tow her in at no cost.



This does not make me feel to good, but what can I do???? He said most customers just wait on them to die and then they replace them. By the way, their was a 99 in the bay next to mine with faulty lift pump which had in turn kiled the high pressure injection pump. The service tech did not seem to be interested in helping me avoid the same fate. They say their hands are tied and chrysler has to approve the warranty work. I understand all of this, but it it ridiculous.



Anyway, I am continuing my bombing. I just ordered a 4" exhaust system from Jardine/Pinnacle. Should be here in a couple of weeks. Already have the PE EZ and will install the injectors soon. Right now I think I will go with the 275's, but am thinking seriously about the DDII's. I am still a little afraid of the extrude honed injectors as they may leak.



later

Don

 

[fj40charles]

Don,



Sorry to hear about the lousy service at your 5 star dealership. The number of stars indicates the number of times they have to scratch their head because they can't figure it out.



I ended up replacing the lift pump even though my truck is under warranty. I don't want to wait for the lift pump to fail so I can damage my injection pump. Instead, I replaced the pump out of my own pocket because I don't want the hassle of dealing with these IDIOTS. I will gladly pay 139. 00 for a pump and not have to worry about waiting 3-5 days for my truck. The last time I had my lift pump replaced under warranty, it took these bozos 3 days to figure out and by the time you factor in your rental car cost and the hassle involved, it is just not worth it.



I don't think you'll have any problems with leaking on extrude honed injectors. I've never heard of this problem.



Charles

 

[GRudy]

Cold presures

I had an interesting one this morning. It was 13 degrees when I left for work this morning. I drove about 2 miles before I noticed that my feul presures were zero! both before and after filter.

The engine was running great so I figured that the feul in the senders must have been jelled. Sure enough after a couple more miles all of a sudden the presures shot up to normal readings... 12 -14lbs.