03 Cummins No Start

I have an 03 as well and went through this exercise last year. Mine turned out to be injectors, which is the last thing you want to replace $$$.

Do you have old lift pump attached to the fuel filter? If so, it may be time to upgrade. Its probably not the problem though. If its hard to start but then running well, its likely the rail pressure is not high enough to fire the injectors when cranking. I saved some notes from my research that may point you in the right direction:

Before trying to start, disconnect the electrical connection from the FCA (Fuel Control Actuator), it is the only electrical connection on your CP3 injection pump. Just squeeze the tab to release and pull, it will come apart.

Now try and start, if it starts you have a low rail pressure condition, by disconnecting the FCA, you have fooled the ECM into believing you have adequate rail pressure. The ECM needs to see a minimum of 3. 5k rail pressure to fire the injector solenoids, by disconnecting the FCA, it by default raises your rail pressure to max pressure. After it starts, if it does, shut it down, you do not want to operate it with the FCA disconnected.

Now you have to figure out why you have low rail pressure, faulty COV, PRV, RP Sensor, Loose cross tubes, bad injector(s) to name a few. I will add a link that will give you a better understanding than my rambling, but the first thing I would do, would be to re-torque the cross tubes. When the engine is cold the tolerance between the cross tube and injector is greater than when warm, thereby allowing more fuel to bypass and lowering rail pressure, when the engine is warm the fuel is thinner, so that could also bypass more fuel, kind of a double edged sword.

Injectors are not receiving the the pressure they need. . . . you can replace the Cascade Valve on the CP3 injection pump. . . .

Before you do that, and free of charge(if your handy), retorque your injector cross tubes to 37 ft lbs. You will need a 24mm and a 19mm crows foot, to fit your torque wrench.

This is an easy procedure, and often overlooked, try it 1st.

For hard starting or no start, Don't forget the CR high pressure sensor and/or relief valve. Either one of these malfunctioning can cause this problem.

You mention you have to prime the engine to make it start? Do you mean starting fluid? The issue you are having is very common and is usually associated with injector ball seat leakage. After time the seat will wear or corrode causing excessive injector return flow. With too much return flow the CP3 can not produce enough fuel pressure at cranking speed to make the injectors fire. Once the engine is running and up to temp the expansion of the injector components will allow the ball to seat enough for it restart, In recent years, Bosch has changed to a stainless body injector design to combat this issue. With the proper tools, you may be able to isolate the problem to 1 or 2 injectors. But since all of the injectors have been subject to the same fuel quality and run time, be prepared to replace them all eventually.

Check lift pump pressure now, before you fry a $1200 injection pump. Anything under 5 while the engine running is bad news.

On the other hand, the injection pump could already be failing.

Either way, don't run it till you know the lift pump pressure is good.

The suggestions about a failing lift pump is better directed towards a 98.5 to 02 VP44 injected trucks. New diagnostic procedures recommend checking fuel flow volume rather than pressure. Typically if you have lift pump failure on a HPCR truck it will have extremely low power or just quit running all together. It is not as common to wipe out a CP3 as it is a VP44 due to fuel starvation but is possible. I agree it should be checked for proper fuel flow, but not likely the problem since he says it runs normal after he gets it started.

Read 71yelladustrs comments..... the rest, pretty much disregard.

03 common rail does not have an "injection pump". The system has a lift/transfer pump that hopefully sometime by now has been relocated to the tank like the 05 and newer. From there the fuel goes to the Cp3 pump which is a 2 stage pump that increased the fuel psi controlled by the ecm via the FCA. Injection event is electronic at the injectors. The line from the Cp3, fuel log, lines to the injectors, crosstubes are nothing more than a reservoir of high pressure fuel.

I've seen plenty of the canister mounted lift pumps die over the years (03-04) to the point that the engine wouldn't start and I HAVE NEVER had to replace a Cp3 pump due to fuel starvation. I've seen them leak, I've seen them not provide adequate psi which in all cases led back to contamination which also affected the injectors.

Very good information guys thank you.The lift pump has been replaced with the intank pump at some time.Ive only had the truck since last spring.I will be taking it in to a local diesel repair shop shortly.They told me it would be $80 to take a couple of hours to diagnose.It has 156K on it.Mid life crisis is here on it im sure.