Injector Pump/ fuel system questions.

[Blacksdieselhp]

What is the injector pump that they are using on the 03-04 cummins? Does it use a lift pump also? What kind of feed pressure does the injector pump need? What kind of lift pump? Where is it located? Are these pumps having any trouble like the VP-44's did?

 

[KLockliear]

CP-3 is the high pressure pump. It does have a lift pump, which is mounted directly to the back of the fuel filter can. Stock, they are about 9-10psi at idle, 5-6psi at WOT. With mods, it drops from there.



They don't seem to have the failure rate like the old ones, but will not support more than 400rwhp... and many won't even support 350rwhp.

 

[Blacksdieselhp]

Can you add a pusher pump to the system? How much pressure can the cp-3 handle without blowing seals?

 

[KLockliear]

The kit we offer doesn't add a second pump, like we do on the 98. 5-2002 trucks, it adds a pump and removes the stock one.



We have run the inlet pressure as far as 25psi with no problems so far.

 

[Blacksdieselhp]

Does it help any as far as supporting more power? I have a system that I put together 4 years ago for the 98-02 24 valves. It does away with the stock pump also. It idles around 18-19 psi and on a 500+ horsepower truck it will come down to 14 psi at wot and imediately jump back to 18 psi. I would like to try it on my 03, but wanted to make sure I wasn't going to blow any seals. Thanks for the info.

 

[ThomasLawrence]

Does it help any as far as supporting more power?

It will. Some people with stock fuel systems have reported dropping the fuel pressure to 0 (or even drawing a vacuum) with nothing more than an Edge EZ.



I'm running an EZ right now, with the DD pusher pump kit, and I've never seen below 10psi. At idle, I see about 14-15psi.



As long as the CP3 pump has adequate fuel flow (not necessarily pressure), it's happy. That means as long as you keep positive pressure between the lift/pusher pump and the CP3, you're doing fine.



-Tom

 

[Gypsyman]

Is the CP-3 still a Bosch unit and where might I find some info on this unit?

 

[KLockliear]

Yep, still a Bosch pump.



As long as you keep the inlet pressure over 6-7psi, you'll be fine. We have experienced missing at lower pressures.

 

[Yo Hoot]

Curiously the Duramax uses the same CP3 high pressure pump (this is not an injection pump per say).



All this pump does is build high pressure into the fuel rail. All the injectors do is listen to the computer and open with electrical signals using a solenoid. But they do it with high precision and fast. . allowing multiple shots per stroke. It is a two stage pump in that it has an integral gear rotor type lift pump that feeds the three piston rotary stage.



What's interesting is the Duramax has no lift pump whatsoever outside of the integral one. It literally sucks fuel out of the tank so you end up with a vacuum in the fuel line from the pump back to the tank.



I believe what Dodge has done is added a lift pump that eliminates vacuum leak issues but at the same time introduces a blockage in the event of lift pump failure. That also may be why the CP3 pump gets starved with higher hp applications. The stupid lift pump becomes a restriction even when it's working perfectly.