I have an 03 3500 5.9. Ok so My truck is dying when at idle the fuel pressure is bouncing up and down also when ever i push the pedal the fuel pressure is going down and it dies. It will run for a min but then it dies even while traveling. I have already changed the fuel filter and the fuel pump is brand new thanks to napa giving me the wrong part. I ordered a lift pump not a fuel pump but the guy who installed it doesnt speak english so we had a communication problem. Please help. I'm a helpless girl!! lol just kidding

 

Your description is vague on what is going on. Do you have low Fuel pressure to the CP3 from the lift pump? Which fuel pressure are you referring too? High pressure or lift pump? It sounds like a FCA issue. I would have the FCA replaced. That is the little solenoid on the high pressure pump call the CP3.

 

The pressure I'm referring to is the one that my gauge is reading.
I'm not sure which one it is. And I'm not sure how to tell which pump is not working. Is that cylinoid expensive?

 

Is your gauge reading low pressures 16 psi and down or dose it read 3k and up

 

It is reading a 5 psi and it usually runs on 10 psi. But it goes down when I push the pedal.

 

That's normal for the pressure to drop down with a stock lift pump. That's not your problem. I would say it is the FCA on the CP3 that is your problem. Get the FCA from Cummins. It will be cheaper than the dealer. You really need someone to check the high pressure pump fuel pressure. On your truck that would be around 5000psi to 20,000psi. I would say you need to find a new mechanic to work on your truck, first. Then go from there. It could also be the fuel pressure relief valve on the rail.

 

Ok thank you. Atleast I have some more info and somewhere to start. Much appreciated!!

 

Internet diagosing is difficult without solid information.

Based upon what you have described so far, I would have to agree with what Spooler says here. It could be the FCA, it could be the PRV (pressure relief valve) and it could be a faulty rail pressure sensor. Less likely culprits are cascade valve or the CP3 itself.

Oh yeah... And Welcome to DTR!

 

Sounds like stock lift pump is on the way out. My oem pump puts out about 10psi no matter how fast I'm, driving.....

 

^^^ apples and oranges.

You have the intank pump that is worlds better than the canister mounted pump she has.

That said, what she posted makes things unclear. It sounds as if she got a new pump... or no?

Also it is unclear if the new (or old) pump is running at 5 psi and dropping (not ok), or is it running at 10 psi dropping to 5 psi (still ok).

More info (better info) is clearly needed.

OP: what other mods are on the truck or is it still stock all around?

 

I have a new fuel pump installed the one that goes in the tank.
I was actually supposed to have the lift pump installed but got sold the wrong part and then had a communication failure.
The worst part about this is I live in a very rural area and there is no one here that is even cummins certified. And the nearest place is 80 miles away.

 

So it is running the same 5 psi with a new fuel pump because that wasn't the problem.

 

The mods are, cold air intake, edge chip, 4 in exhaust. And I think that's it.

 

It won't stay running longer than about 30 seconds.

 

What fuel pump did you put in it? The intank pump psi's are around 8-10psi. The on the fuel canister pump is normally around 7-8 psi.

Which Edge product do you have. If it is the Edge pressure box (don't remember the name) then it is more than likely the cascade valve due to the added pressure. First thing to try always is to pull the box off and run stock to see if you still have a problem. I would leave it stock until you get it figured out.