lift pump pressure?

[Sixpac2]

I was trying to find the spec on lift pump pressure in my 04 service manual ( on CD). It talks about the low pressure gear pump pressures and the high pressure pump. Does any one know where to find the spec pressures on the lift pump?

 

[Roger rodbolt]

My 2003 manual shows 11. 5 psi minimun for the lift pump (going from memory here) and I can't find any pressure spec's in my 2004 manual. HTH's Larry

 

[Cattletrkr]

Was at the dealer today and asked the same question. The lady at the counter couldn't find it and the diesel tech didn't know off hand. He said the 03's should be 15psi, but the 04. 5's are supposed to be different. Of course this is coming from a dealer... :-laf

 

[Summit]

04 pressure

i've never seen more than 9 1/2 psi @ idle on my 04. the new ones dont have 14-16 psi like the 2nd gen trucks. my pressure is very erratic though kinda like it has a short or something. my tech said that they dont have a constant 12v to them. the ecm gives a pulse of 9v. sounds kind of wierd.

 

[gsdog1]

Pretty much bone stock here with a little over 5k on the ticker. 7 at idle, 6 at cruise, and 5 at WOT. I have no idea what the actualy specs are though.



Matt

 

[Sixpac2]

the manual says that the "maximun current flow to the pump is 5 amps. and with the engine running the pump has a 100 % duty cycle. "

QUESTION, the duramax has no lift pump and is a suction feed system from the low pressure gear pump incorporated in the injection pump. does any one know if it is a totally different injection pump? and why do we have a lift pump and duramax does not?

 

[Sixpac2]

summit, where are you and or how did you hook up a fuel pressure gauge? I have seen the billet fuel cap from genos garage is there another way for the 04. Thanks

 

[rbattelle]

My '03 manual has a minimum spec of 9. 5 psi at the injection pump. I was not aware that the lift pump is running on 9v pulses instead of continuous 12v. Can anyone verify that? Sounds odd to me.

 

[rbattelle]

my tech said that they dont have a constant 12v to them. the ecm gives a pulse of 9v. sounds kind of wierd.

Okay, I did some research and have found this information is false. Page 260 of the 2003 Powertrain Diagnostics Manual indicates that the lift pump must recieve a minimum of 11. 5 volts to run. Therefore, the correct lift pump supply voltage is a continuous 12v, as I suspected. Your tech is wrong.



Also, for those looking for more specs:



Maximum LP inlet restriction: 6 inHg (2. 94 psi)

Minimum fuel flow rate: 40 ml/s (38 GPH)



-Ryan

 

[Summit]

summit, where are you and or how did you hook up a fuel pressure gauge? I have seen the billet fuel cap from genos garage is there another way for the 04. Thanks

i have a mechanical autometer 0-15 psi guage that i had on my 01 that i kept when i traded. i stoled a shrader valve fitting off of my wifes 01 and removed the valve. it's located on the bottom of the filter canister / post filter.

 

[DCTECH]

On 2003 Specs Are 11. 5 Psi At 100% Duty Cycle At Battery Voltage. specs On 2004 Are Only Listed In Volume In Millilitres During Pump Running For 10 Seconds. Need 40 Millilitres Or More And Less Than 5 Inches Of Restriction.

 

[LEPage]

It is my understanding that there is no pressure spec, it is a flow rating. I can tell you the CTD CR needs the positive pressure to run. Mine dropped off and the truck fell flat on its face over 2,000 rpm. Changed fuel filters, pressure came back up, and truck instantly ran OK again. My pressure varies from 9. 5 with new filter to as low as 5 at idle. I change filters when WOT pressure drops below about 2, and am good to go.

 

[Sixpac2]

QUESTION, the duramax has no lift pump and is a suction feed system from the low pressure gear pump incorporated in the injection pump. does any one know if it is a totally different injection pump? and why do we have a lift pump and duramax does not?