i have been going to the dealership to try and find out what has been going on with my diesel truck. there seems to be a weird knockin in the engine and they claim that it is only carboned up. but thats not all of it. every morning when i fire it up the truck does not idle correctly, it bogs down to almost 300 rpms and all the sudden revs up to 1800 and then it will bog again..and that will happen repeatly until its warm then it will go on high idle normal...it makes weird noises and sometimes, even when u are drivin in the city it will do the boggin at stop signs and at red lights... it does not run smooth at all...out of nowhere it will start blowin black smoke and then all the sudden stop and runs normal(but still with the weird knockin) wether the knockin and the boggin are related im not positive. but the boggin has to stop, tonight i am parkin the truck at the dealership so that they can fire it up in the morning to see what it does....
do u guys have any idea of what this problem could be..maybe fuel pump..i have changed my fuel filter as soon as this boggin started happenin but didnt help any...sometimes its like the truck is going to die...
please help!

 

could be bad injectors, hows the oil level... are you seeing the level going up? ( leaking injector) pick up one of those infra red tempature guns at any good auto part store. get your truck up to running tempature using the temp gun shoot each exhaustport on the exhaust manifold. they should be consistant tempatures if you see a colder exhaust ... that injector is hooped.

also check out the FCA = fuel control actuator on the back side of the CP3 injection pump, famous for sticking causing rough idle/poor pefromance.

if you do find an injector or mor colder then the rest, I would sugest taking it to a good local diesel shop for remanufactured injectors alot cheaper then what the dealer is going to charge. thats if you are unable to do the work yourself.

could also be the lift pump, but the way its acting most likely not as the injection pump has enough jam to run the engine well enough where its not acting like yours. (GM duramax use same injectors and injection pump as the cummins but they don't have a "lift pump" like we do)

 

picture of where the FCA is??

 

Here is requested picture of FCA... it will have an electrical connection to it and 3 torex bolts to remove it. Its on the back side of the injection pump, the pump is located looking from the front of the engine to the back, on the right side front of block, you can also trace fuel line from fuel filter to front on engine and that would be the injection pump.

Make sure area is clean before removing it (so as not to get any dirt into the injection pump) it has an O-ring on the backside of FCA so it will take some to pull it out. Some say you can check the working condition of the FCA by shaking it, if it rattles its suppose to be good, but that won't deermine if the solenoid is woking? Best place and cheapest to purchase new one is at a Cummins dealer.

 

yea, well so i was at work today, and i take off for lunch to go home and i fire up the truck, runs fine for like 5 seconds and all the sudden it dies....
dealer is sayin first thing is to drop the tank and drain fuel and clean system but i really dont think that the truck runs fine except only on start ups that it dies, and sometimes bogs down...
im not sure what to do anymore i dont even know if my diesel fires up in the morning or not...

 

My 2003 5.9 does the same exact thing. Anyone have any ideas?