Engine/Transmission (1998.5 - 2002) proper fuel pressure

[MIvy]

A 2002 5. 9 standard trans 160,000 miles with original lift and injector pumps. The fuel pressure at idle is 9psi and 6 psi at 2000 rpm in neutral. What should the fuel pressure be? When driving the truck it has what is described as dead pedal. Have replaced fuel & air filters. It has a code showing bad injector pump. The tentative plan is to install a new lift pump.

 

[Sticks]

A search would have turned up tons of answers.

From the mouth of Bosch ~ "The VP44 injection pump used in the 24v Cummins application requires a minimum of 10 psi fuel pressure at all times. "

So, 10psi is your minimum regardless of idle, or wide open throttle in a sled pull (a max of 25 psi ~ too much is bad as well). Less than that you are damaging your VP due to lack of cooling and making the VP draw fuel in when it is supposed to have it pushed in.

What code(s) do you have other than P1693?

 

[PC12Driver]

Ouch... 6 psi no-load is not a good sign. Stock should be in the low teens at idle and not much change if you rev it in neutral. Under load a stock setup should be around 9-10 psi. If you catch the low supply pressure early (onboard fuel pressure gauge) you can probably save your injection pump. Unfortunately, by the time you notice symptoms in throttle control, the damage is done to the injector pump. Probably due for a combo meal (new injector/lift pumps).

BTW, if you've made it to 160,000 miles on the original stuff you're waaaay above average!

 

[Joseph Donnelly]

A good lift pump would give 16 psi at idle.

 

[RonaldLarson]

Yes, your IP is dead. Dead pedal was my malfunction from not monitoring pressure, and a bad lift pump. I've had a Raptor pump on my truck for six years, and never see below 12 PSI towing, with big injectors and a fueling box fro Edge.