2005 dodge 5.9 cummins

1st the lift pump failed
I had the dealer replace it and they also sucked me in for a #5 injector
then I added a K&N cold air intake and a hypertech max energy programmer
everything was fine
great performance and 18 mpg
after about 2 weeks I all of a sudden have sluggish performance and 12 mpg
just feels like no matter what program I use it has no power and uses more fuel
but it still is quite drivable, no bucking or stalling or starting problems
I was thinking injector pump but not sure how to tell
also do not want to return to dealer that after I told them I was having lift pump failure do to the very specific symptoms they started by screwing with the injectors first
wouldn't you first check to see if the engine was getting fuel?
anyway, if it seems like injector pump I have heard that buying most rebuilds you are still getting a pump with a bunch of somewhat worn parts
could use some expert advise

thanks
Tafster

 

I have ben working on these trucks for years. I still have yet to see a dead CP3 on a Cummins. The Duramaxes go through them at about 168,000 generally.

I would guess a sensor before anything else. You have a cam shaft position sensor that goes out every now and then on the common rails, the FCA is a sneaky little basterd as well, but you would have more symptoms than just a lose in power so I doubt it would be that.

The problem that I see right off the bat is that they only replaced one injector. Injectors go out in pairs. Every time I get a truck in here with a bad injector I always replace the sister injector that is on the same firing order. You may just be feeling the other injector going out.

The firing order on your engine is 1-5-3-6-2-4 if number five injector was dead chances are number 2 was following right behind it. This is just my personal experience it may or may not be the answer to your problem.

I know for a fact that those factory replacement lift pumps are junk. I know they replaced it for you but I had 3 factory replacement pumps in my 2003 by the time I hit 75,000 miles. Spend the money and get yourself an Air Dog 150.

It will save you a small fortune in the future. The Air Dog pumps kill two birds with one stone, they replace the inferior factory lift pump and also filter your fuel to the micron specification required for your Bosche injectors. Those injectors are supposed to be filtered down to 2 microns. The factory supplied fuel filter provided by Chrysler is an 8-12 micron filter. That is allowing chunks of crud 4 times larger than you should have to pass through you injectors.

Get rid of that K&N filter also, your stock filter is better than a K&N.

We strapped a bone stock 2005 cummins down on the dyno and tested a couple of different intakes on that truck, same day same dyno and we allowed half hour cool down times between intakes. We dynoed 5 horse power less than stock with a K&N cold air intake and 23 horse power over stock with an AFE, S&B & an AEM. Those K&N's are junk.

I hope you get this figured out soon. They can not truly tell which injector is bad without taking them out and flow testing them, not POP testing FLOW testing. Dealership mechanics are some of the worst people in the world to deal with. I've been fixing F#$K ups for the two local dealerships here for years. They usually have no idea what they are doing or talking about unless they can read it in their little book.

 

good advice

 

great
sounds like you know your diesels
I am looking for a knowledgeable diesel mech in my area
ft laud ,fl
I don't want to return to the dealer
I am looking at the air dog 150 also
is that a user replaceable part or do I need a pro to set it up?
thanks for all the advice and info

tafster

 

did you ever figure out why you lost power and you were getting 12 mpg? im having the exact same problem with my truck. i saw your post when i was searching for answers.