04 cummins loses rail psi when normal temps are reached
 

my buddy just bought a 04 or 05 cummins it runs great until it hits normal operating temps then it starts acting up when u come to a stop sometimes it will die at idle it kinda has a slight ruff idle if u listen really close the grid heater light comes on and it loses all its pwr for some reason he checked his rail psi and its fine until it gets warmed up the it drops to like 1500 or so truck is mostly stock besides airdog and smarty we was thinking the fca the truck has almost 200k and he was just going to buy a new cp3 with the fca 30%over stock let me know what yall think thanks guys:c:

That's my guess! Swap FCA out if you have a cummins or someone you know!

A $100 FCA is a whole lot cheaper than an entire CP3...the CP3 is pretty durable.

how many miles do they usually last till the puke on a bone stock truck

I've got over 250k on mine, and its been abused....water killed injectors at 140k and the FASS died at around 230k and I was forced to drive 2100 miles without a lift pump, and it lives. They are pretty tough. You don't really read of too many CP3 failures.

How full is the fuel filter? I know that sounds silly, but. When its cold it is a bit fuller then hot. When it heats up you could be starving the high psi pump. If you really want to know if the pump is bad, bubbles in the return line is always a sure tell, provided there are no leaks in the fuel system. I don't know how the engine has been cared for, but it could be a head gasket issue too, don't change the coolant, and you'll be changing the head gasket. look for bubbles in the rez for that. And as always, it could be just bad fuel. Hope that helped

im not sure on how full the filter is but when he first got and and it started doing it he was thinkin posible bad lift pump so got an air dog and didnt help at all its just weird it will run awsome all the way till it hits 190 200 and then you might as well give up on being able to drive it and for sure wont pull any trailer i will mention the head gasket and have him check his resi thanks for the ideas keepem coming as soon as we get it resolved i will post the cure:c:

Re-torque transfer tubes, typical symptom.

In all , I forgot to ask. What temp does the computer think the engine is running at? oil psi and temp too. Is it going to limp mode thinking it has to save the engine? coolant level will set it off too, but thats a shutdown.

oil psi and engine temp run exactly computer to gauge and changed the FCA and didnt help anything coolant is where it should be still throwing no CEL but when he check the codes last it was saying throttle pos sensor curcuit high i think is what it said i think he is ordering a new cp3 this week