I was recently having a discussion with a buddy about the dodge vs the duramax. he bought his truck about the same time as me and this had been our first real chance to compare thoughts. After some talking i mentioned something about the cp3. He said oh, thats cool we have the same injector pump. then we started talking about how is older dodge had the lift pump go out. He then said he was glad he didnt have a lift pump any more. How come our cp3's cant run without a lift pump and the duragays can? does he know what he is talking about. I did some surfing around on some duramax forums, but there were to many people with to many problems to sort thought to even begin to try and get information. Any body know if this is true? is it the same cp3, is it even a cp3?

 

our lift pumps are inline from the tank to the cp3. when the l/p fails, it becomes a restriction that the cp3 cannot pull through. hence, the truck will not start, or run well.
There are other reasons as to why is isnt quite the same but its 11pm,and my mind is mush.

 

The LB7 and LLY Duramaxes didn't have a lift pump. The new LBZ Duramax does have a lift pump from my understanding.
Having a lift pump does make it easier to prime the system after a filter change.

MikeyB

 

Our trucks -will- run on just the CP3 and no/failed lift pump. It will start perfectly, but I wouldn't ask for much power running this way. It will get you where you need to be for repair though.

Chris

 

The cummins CP3 will run without a lift pump also, the same as duramax. Dodge or cummins decided they wanted an easier way to prime the fuel system after filter replacement that's what the lift pump is for. If the lift pump fails then there is too much restriction for the cp3 to suck fuel through so the engine dies. The lift pump will also allow more hp without starving the cp3 for fuel. When the duramax guys increase their hp beyond x amount they put a lift pump in place to help supply more fuel to the cp3. The duramax uses a primer bulb to pressurize their fuel system after a filter change.

 

guess that is good knowledge. So our lift pumps are out side of the tank? is that why everyone running mods runs the intank setup?

 

the 05 and ups are in the tank from the factory. Earlier years had them mounted on the fuel filter housing. Either way if you upgrade the fuel system most people rely on an out of the tank pump.