As many of you will recall, I like everyone have been chasing this problem for along time with my 2003 cummins. I have been trying various methods of troubleshooting, thought I would share my lastest one because I haven't have a hard start in along time.
When the dealership did the MOD to the intake fuel pump they changed the harness and put in the timed relay. The pump will supply pressure for I think 20 seconds before turing over the engine. I put the FASS system in shortly after and used the harness that came with the FASS system. The hard starting problems starting shortly after the FASS pump install.
Here's my secret so far!

When I go to start the truck I just cranked it over, don't let the light go out, and I don't let the pump prime the system. My theory is the pump is pushing fuel into the injection pump and flooding the cavity with fuel. I might be way out in left field but it starts like the day it was new everytime in the freexing cold. The way the system was when it was new did not prime the system before the truck started. Guess the timed relay was another crazy rediculous chrysler idea that doesn't serve any good purpose. I a still not totally convinced this has fixed the problem so I haven't removed the timed relay yet(back to stock,stock) but I plan on it soon. Its been along time coming but I am really confident I've got it.

Cheers

Greg

 

Greg,

I don't know what you mean by "flooding" the pump. It must have fuel and it does not want air. Fuel pressure from the lift pump is needed to start. Or at least no restriction on the CP3 suction side and no air.

It sounds more like you might have a suction side leak that is letting air into the CP3 overnight. That air must get out and fuel must be present before it can start. You can't flood a diesel like a gasser, flood meaning too rich to start. But it's confusing how yours starts if you don't wait and not if you do wait, is that right?

Mine has the delay too. The lift pump (Walbro) comes on immediately with the key. If I don't start it, the pump runs for about 25 seconds. So it is an immediate on and delay off. Works well for purging air after a filter change.

The only reason you should ever have to wait to start is if you are in an extremely cold environment and need the grid. Mine starts just fine without the grid at 5000 feet elevation with a temp of about 10-15 degrees F.

I tested mine the other day by just turning the key with no pause at that low temp. It started on the third compression stroke! Faster than normal in warm weather, where it usually takes about 10 compression strokes.


John

 

The orginal configured fuel system did not have a timed relay controlling the lift pump before turning over the truck to start.
I read somewhere a while back the injection pumps in the 2003 and beyond can suck fuel to some degree without damage. My understanding was the timed relay was brought out in the later models because the VP44(injection) pumps where getting eaten alive. The same mode ended up getting put into the 2003 and beyond before the trucks started coming out with the mode installed factory.
I am curious if anyone has just attempted to start there truck without letting the pump prime the system. Not even sure if the system is priming because there should be fuel in the system. I am convinced the FASS pump was pushing fuel into the injection pump and possibly causing pre-detination before the truck really did fire up.
Just wanted to give my two cents, my hard starting problem seems to be solved and I didn't drop over 3k on new injectors.

Cheers

Greg