2003 24v 5.9: Hard start when at operating temperature

[BrokenGermanDodge]

Hello all,

I really do like this truck but it has been giving me a fit recently. It is a 2003 3500 5.9 Cummins Automatic

The problem started after it almost dropped a valve. I had the cylinder head redone, and it ran great for a little while.

Once the engine is up to operating temperature, the truck will not start. When it cools off, it will start once again.

The lift pump was already weak so I replace it. No change.

Injectors are new, but are 60 over aftermarket units. If necessary I will check them, but am unsure of how to do so.

I have checked:

1): The supply line that leads to the filter housing does deliver fuel
2): The line from the filter housing to the high pressure pump also delivers fuel
3): The filter itself and the seal around the top cover have been replaced
4): All the lines themselves have been checked for weathering and cracking, one was replaced but the others were fine.


I had checked the pressure relief valve but i am unsure of what to look for. I had cracked loose the banjo fitting that leads to the fuel filter housing. It looks as though it splits off back to the high pressure pump. If the truck starts, the line sprays fuel. From my understanding the check valve has not yet reached 27kpsi, so it shouldn't be spraying fuel.

Any advice on where I can go from here?

 

[BrokenGermanDodge]

Update):

5): Removed hard lines from common rail and re-torqued the supply tubes. No change
6): Plugged the pressure relief valve on the common rail. No change

Could anyone point me to where I should go from here?

 

[Travelin Ram]

When I hear about hot no start it leads me to think of electrical components that have heat soaked. Maybe the Fuel Control Actuator the PCM uses to control the pump?

 

[BrokenGermanDodge]

Ill give that a try, Truck is running right now to warm up and replicate the hard start. If it goes away with FCA disconnected (hopefully) then ill go get a new one.

 

[BrokenGermanDodge]

Not sure If i was doing it wrong. As I dont fully understand how the FCA works. Truck was run until it was hot enough so that it would not start.

Disconnected the FCA: Started immediately. Then shut truck off

Reconnected the FCA: Started immediately. After this, I was puzzled, maybe I hadn't adequately replicated the no start because the engine was not heat soaked enough, so I took it for a drive.

Once back from the drive I:

Disconnected the FCA: No start

Reconnected the FCA: No start

I presume I can now rule out the FCA.

Interestingly, once the engine was good and heat soaked (I know its bad) I sprayed the injection pump down with water. After this, it started.

I guess I should start looking at injector return? Unless if cooling down the injection pump, and it starting thereafter, is a conclusive result.

 

[alnelson14]

Your CP3 is failing. Ensure the lift pump is supplying proper pressure to the injection pump as the leading cause of injection pump failure is low supply pressure.

The cp3 will draw from the tank but its hard on it. The fact you could cool the pump and it started is surely the pump on its last leg.

 

[RedneckHippy]

So maybe you were right swapping out that lift pump, but the damage had already been done to the injector pump.