kyjr.buggy1 wrote:
The CP3 is an injection pump. Usually diesels have lift pumps. The LBZ Duramaxes DO use lift pumps, the LLY, LB7, and LG4 do not. The common rail cummins, and the vp44 pumped Cummins use lift pumps. The 12v Cummins (HOO RAH) uses a block-mounted lift pump. On the Duramaxes that don't have a seperate lift pump, there's a high pressure side and a low pressure side of the CP3 pump. The low pressure side pulls the fuel from the tank to the motor, and the high pressure side delivers the fuel to the fuel rails. Duramaxes WITH a lift pump still have a low-pressure side of the CP3 pulling fuel, but the lift pump helps shove the fuel to the pump. The only reason the CP3ed Common Rail Cummins started using seperate lift pumps was to make it easier to prime the fuel system after a fuel filter change, etc. Same for the Duramaxes. They can both run with a failed lift pump, or without one, they just won't get as much fuel, resulting in a power loss. That's why the LBZ Duramax is rated with more HP/TQ than the other Duramax engines, because it uses a lift pump, allowing them to turn the fueling up from the factory.
-Dakotah/koko
thanks for the info koko, i was confused because i have an 06 cummins and was 99% sure it had the cp3 injection pump on it but i was also 100% sure it had a lift pump
