Engine/Transmission (1998.5 - 2002) 24 valve lift pump presure ???

[Aliff]

I have a 99 4x4 manual trans truck with 100k . When i checked the fuel psi at the top of the fuel filter I found 11psi at idle & 6psi at full throttle. Is this normal ? Should I check volume ? If so how do i do this? Im not having any problems with the truck but i wonder if it would run even better with a new lift pump since the origional pump has over 100k. anyone???????

 

[Tom W]

That's a little low but mine is the same. I'm no expert but as I understand it, as long as you have positive pressure in this range you are OK. I don't think you would see any performance improvement with a new pump. The lift pump does little to help the injection pressure, the lift pump pressure is necessary to cause the fuel to return to the tank which cools the injector pump. As I said I'm no expert, all I know is what I have learned on this site. If I am wrong somebody will let me know.

 

[CumminsFarmer]

That pressure is too low. You should be reading between 15 and 16 psi at idle, and it should NOT drop below 8 psi under load. If it does then your having pump troubles. If you want to do a volume flow check then unhook the fuel line from the tank at the lift pump and bump your key. Have it pump into a measured container. It should pump 40 oz. of fuel in 25 seconds. You should be able to take it into a dealer and have it all done for free, including a pump replacement. Should be covered under a Cummins warranty good for 110,000 miles.

 

[johncameron]

You should be able to take it into a dealer and have it all done for free, including a pump replacement. Should be covered under a Cummins warranty good for 110,000 miles.



The cummins warrenty is 100,000 miles? Doesn't it?

 

[CumminsFarmer]

I thought it was 110,000 miles but I cant guarantee. I had my pumps replaced last summer at 87 grand, one of my friends lost both pumps at 111,000 and they "grandfathered" him in and gave him warranty. Dont know for sure.

 

[jbone]

Guys, Gave up on Dodge wanting to do anything after 36,000, so bought my new pump from Cummins and reads 15 lbs all the time period... . R, J. B.

 

[mhenon]

I have a 99 4x4 manual trans truck with 100k . When i checked the fuel psi at the top of the fuel filter I found 11psi at idle & 6psi at full throttle. Is this normal ? Should I check volume ? If so how do i do this? Im not having any problems with the truck but i wonder if it would run even better with a new lift pump since the origional pump has over 100k. anyone???????

I'll bet the dealer say's: " It's just fine". Then you'll get charged for the check-up.

 

[JTruelove]

I just had both pumps replaced less than a month ago. The readings I have our between 10 & 12 @ idle and it never gets below 7 @ wot.

 

[CumminsFarmer]

Mine went out around 87,000 and the dealer troubleshot it, installed both pumps (VP44 was damaged), and warrantied it thru Cummins with no charge to me. Maybe Im just lucky.

 

[jjordan1]

I just had mine changed on my 2001\2500 w\56000 miles. It was done by the dealer @ NO CHARGE

 

[jelvington]

I had my dealer check mine when my gauge crapped out. It checks 14 at idle and drops to 6. I got charged $65 for the test. I still question the decision not to replace it. I keep reading of guys replacing theirs and never dropping below 12 or 13. I also read that it should never get below 8psi. I just wish that all of these dealers were the same about replacing under warranty when the pressure got down to a certain reading. I have about 95000 miles on my truck and I would bet that if I take it in after 100k with the same reading they will say it needs to be replaced..... at my expense of course. I am saving all of their test printouts for when that happens though. My gauge is fixed now and it still reads what the dealer got.

 

[GLASMITHS]

I had my dealer check mine when my gauge crapped out. It checks 14 at idle and drops to 6. I got charged $65 for the test. I still question the decision not to replace it. I keep reading of guys replacing theirs and never dropping below 12 or 13. I also read that it should never get below 8psi. I just wish that all of these dealers were the same about replacing under warranty when the pressure got down to a certain reading. I have about 95000 miles on my truck and I would bet that if I take it in after 100k with the same reading they will say it needs to be replaced..... at my expense of course. I am saving all of their test printouts for when that happens though. My gauge is fixed now and it still reads what the dealer got.

I just changed mine at 108K. Had been at 12/7 for 3 years with no problems. Was afraid to take it to this dealer for anything. So went to NAPA and popped for 175. for theirs. Now 17/12. Maybe the older trucks had lower pressure to start. Just changed mine cause I was skeered :-laf Didn't want it to crap on the road.

 

[rblomquist]

On the 99 it depends on which port you're taking the reading from as well. If you're taking it post-filter (port closest to the front of the truck) then you'll read some psi lower just from the fuel running across the filter. You also didn't mention when the last time a new fuel filter was dropped in, that could be part of your problem if its been in there forever and/or you've got a little dirty fuel here and there.

 

[GLASMITHS]

Dirty filter? Nope. I change mine before each major trip. Have had to change 3 on the sides of the road :{ :{ with less than 1000 miles on them. The one presently in has been there about 5k. That is a long time for me.