Alright, my buddy has a 01 Dodge ram 5.9 cummins. he just replaced the lift pump. Everything worked fine before. Now it will only crank in the mornings or when its cold. After it has been ran a few minutes it will not crank unless you lift that pressure release valve while trying to crank it. By doing that it cranks every single time. He said he went through the process of bleeding out the air through the injectors and everything. If it cranks good first thing in the morning or when its cold, what could be causing this?

 

what exactly is it you are calling a pressure relief valve?

 

He didnt really know what it was called but Its on the lift pump canister. You can flip it up and fuel will pour out the bottom of it. What ever it is it helps it crank. He says he is thinking its the sensor that is on top of canister.

 

that shouldnt have anything to do with the engine cranking.... thats what your saying correct? or is it the pump not running? if you are talking about the engine cranking over, he must have a bad connection with the starter/wiring, fuel pressure will not effect the engines ability to crank over

 

It will spin over it just wont crank and run unless you pull the drain lever on the fuel filter canister.

 

now my brain is burning not sure what you mean, is it the engine is turning over, just doesnt want to fire?

 

well we figured it out. It ended up being the injection pump. The new lift pump was causing something inside the injection pump to mess up. maybe too much fuel pressure on a worn diaphragm or something?? We disconnected the lift pump and tried cranking it. Guess what.. It fired right up. We cranked and killed it about 6 times. So what we did was cut one of the wires on the lift pump and ran it inside to the drivers power window switch. We did that because when the trucks ignition is being turned over the power is shut off to that switch which would keep the lift pump from running until the key is let go for normal operation. We have been told that this would work for awhile but eventually it would start having problems again.. In the mean time my buddy is looking for someone to rebuild it. Just thought i'd drop in and let you know.