2016 Ram 3500 mega cab SRW 6.7 cummins . So I recently completed the EGR and DPF delete. I also installed the Ezlink tuner as well as a S&B cold air intake. Also installed the EGT solution kit that relocates the EGT sensor to cylinder 6 on back of manifold. I had download several tunes and trying them out. I use the truck as a daily driver as well as towing my 43’ fifth wheel. I have a 460 mile drive every Thursday and Sunday. I tried the different tunes along this route looking for best fuel economy. Naturally the 150hp tune gave the best results. All was good for about 2 trips then it started running ruff when I would kick it down and pass cars. It almost felt like a rev limiter. I called GDP up and we ran a data log on it from 0-60mph. While performing the test it ran ruff and we got the P0087 code. The tech also said I was only pulling about 12,400 psi on the rail and it should be about 26,000psi. I know from personally experience if it was only a fuel filter that could usually only account for about 4,000 psi. So I’m not sure what is going on. Could it be a fuel rail sensor, could pressure relief valve be bad( do i need to plug it) is the lift pump clogged up or do I have a fuel pump going bad. Any ideas before I start dumping endless amount of time and money at it.

Easiest thing to do is plumb in a gauge and see what sort of pressure you are getting to the CP3, that is assuming that the fuel filter is indeed fine. How many miles are on the truck?

 

I had a issue where it sucked water into the system and destroyed the whole system before I could stop. It still ran, but very poorly and had a dead miss. ~$9000 at the local diesel shop for all 6 injectors and a CP3.

On 9/24/2020 at 9:09 PM, That Guy said:

Easiest thing to do is plumb in a gauge and see what sort of pressure you are getting to the CP3, that is assuming that the fuel filter is indeed fine. How many miles are on the truck?

 

I had a issue where it sucked water into the system and destroyed the whole system before I could stop. It still ran, but very poorly and had a dead miss. ~$9000 at the local diesel shop for all 6 injectors and a CP3.

Did you ever figure out how you got water in the system?

Low rail pressure is typically a rail leak. I've seen crossover tubes come loose and leak into the return rail. I've seen totally wore out injectors drop rail so bad if it did start it wouldn't idle and stall again. Rare for CP3 to fail typically do rather well for long time as long as the lift pump keeps up.

 

I've got to ask how many miles on the injectors? If it over 150k miles you due for fresh injectors very very soon. Liker my 2006 Dodge 3500 we ran it back and forth for a day and filled the crank case up with extra 3 quarts of diesel fuel. I've got 189k on that truck and all 6 injectors got to be replaced. I've got 2 more Common rail trucks to do injectors on soon. One currently will not start at all. The other one is starting and running but all injector have codes.