Engine/Transmission (1998.5 - 2002) Replacement lift pump pressure low.

[Ponz]

Some time ago I relocated the lift pump to the frame and up-graded to a Carter 4601HP pump that is supposted to be good for 18psi. The original 4601HP had 12psi @ idle and 6psi @ WOT and lasted about 1. 5 years, when it started to loose pressure. Back to NAPA for a new pump and it only held 9psi @ idle. Back to NAPA again and they gladly replaced it with a new 4601HP. Same problem, only 9psi @ idle. I have a 3/8 draw straw and 3/8 Gates rubber hose all the way foward. Checked also for any kinks or restrictions. I'm stumped, need some advise. Thanks, Ponz

 

[DPelzl]

When you were getting 18 lbs did you have the large lines installed? I am thinking with larger line your pressure should go down but volume should go up? From what i have learned Volume is the key.

 

[Ponz]

I installed the 3/8 line when I moved the pump. The highest psi I've had was 12psi @ idle even though Carter says the pump is good for 18psi. Southern Plains Generator , a Cummins suppier, says 10psi @ idle is good.

 

[Ponz]

help please

 

[Doug1810]

i read in hear that 13. 5 at all times is what you want . i run the 7 psi carter with the 15 psi cater with no problems . pressure at 16-20

 

[Jeff Knight]

Have you changed your prefilter lately? Is it cold where you live? I was thinking the pump was having a hard time pulling cold fuel through your prefilter. Just a thought. Jeff

 

[Ponz]

Its not usually cold here in Texas. I changed both the prefilter and the fuel separator. I've sent an e-mail to Carter Federal Mogul. Still need help.

 

[Ponz]

bump up top

 

[fox]

Just put an aftermarket pump on it and be good to go!!

I am using the Glacier pump. Never less than 15, with a high of 18.

I have changed a few of the carters too, never satisfied with 12 at idle dropping to 3 at WOT.

 

[DPelzl]

Ok i did a little searching here on TDR and from what i read from people that know allot more than me is 12-15 lbs is the recommended pressure you should be sending to the Vp44. Can you give it more pressure yes but to much pressure can hurt the pump. The magic number is 5lbs. If you go below that you can starve the pump and more importantly over heat it because there may not be enough fuel running through and back to the tank to cool it. The VP44 draws about 3lbs itself. As long as there is an adequate supply of fuel there, all is good. Pumps like the FASS are high volume low pressure pumps and because there is so much Volume (95gph or 150gph) there is very little pressure drop from Idle to wot 2-3 lbs. Take a look at Blue chip diesels tech articles on the vp44. http://www.bluechipdiesel.com/VP44INFO.html. Also search for lift pump here in TDR there is some great info. Now with that being said would i be happy with 9lbs at Idle? No thats why i bought a FASS but i would not be that worried about it unless you can pull it down below 5 lbs.

 

[Ragain]

As long as there is some kind of positive pressure you'll be fine. VP-44 trying to pull a vacuum= death. I have put brand new Cummins/Carter fuel pumps on that were bad from the get-go. Don't just assume a new pump is a working pump.