Help!!!! Low Rail Pressure!!

[dan shss]

At Idle i have 6k rail pressure,Unpluged FCA at idle and have 25k rail pressure,Reved up in neutral can hit 15K...

When I am On the road and floor it my rail pressure will drop to 3kpsi and the truck obviously has no power at 3k rail pressure... If I give it 1/2 throttle the rail pressure will come back up to around 15k. .



I have a steady 15psi supply to the cp3 the hole time. .

 

[Rams-n-Hogs]

At Idle i have 6k rail pressure,Unpluged FCA at idle and have 25k rail pressure,Reved up in neutral can hit 15K...

When I am On the road and floor it my rail pressure will drop to 3kpsi and the truck obviously has no power at 3k rail pressure... If I give it 1/2 throttle the rail pressure will come back up to around 15k. .



I have a steady 15psi supply to the cp3 the hole time. .

Sounds like you need to upgrade your CP3, or turn your boxes down.

 

[DPashko]

maybe your CP3 is going, your rail relief valve is sticking open, or you CP3 actuator is hanging up... just a few thoughts

 

[RMalone]

I bet you have an injector problem, do you know for a fact that the injectors were installed with the proper torque specs? I had a problem very similar to yours. I replaced the FCA to no effect and I could get good rail pressure at idle and with the FCA unplugged, but put it on the road and throttle it up and rail pressure wouldn't hold. I never saw anything as low as 3k psi, but it was smokey, hot and underpowered at 14k psi. I replaced all six (used sticks bought from a TDR member) and problem fixed. I see you have Flux2's, see if your dealer can get in touch with DonM to help you troubleshoot, best of luck, rail pressure issues SUCK.

 

[dan shss]

All my boxes are unpluged,rail is capped, injectors are new,all filters are new,I tryed a spare FCA that didnt help,spare map sensor that dint help.



I guess I will retorque the fuel transfer tubes,My oil has no fuel in it.



I have no codes ,engine runs good except when you floor it under a loud the rail pressure goes down to like 4k, I dont know if the electrinocs are not telling the cp3 to fuel our if cp3 is bad???????

 

[AMassaro]

I have 4200-4500 pressure at idle. No other issues though... .

 

[RMalone]

Don't just re-torque the crossovers. I would loosen the injector hold downs and pull the crossovers for a look then repeat the entire torque sequence. You might as well eliminate all the variables you can while your in there.

 

[dan shss]

Don't just re-torque the crossovers. I would loosen the injector hold downs and pull the crossovers for a look then repeat the entire torque sequence. You might as well eliminate all the variables you can while your in there.

If the cross overs are leaking dont they leak fuel in the oil??

 

[Scrappy]

If the cross overs are leaking dont they leak fuel in the oil??

it shouldn't, there is supposed to be a return passage in the head that will return the leaked fuel back to the tank. are you having hard start issues? if it is leaking at the tubes it can cause it to be hard to start.

 

[Summit]

how big of sticks did you go with? sounds like your draining the rail to me, do you have a fuel pressure guage to? if the lift pump is weak it'll drain the rail too.

 

[dan shss]

I just have Flux 2,s I have Fass150 my supply psi Stays constant 15psi. .



I think the cp3 is just not putting out enough when its under a load,, I can do a burnout in first gear and it will hold 15k psi rail pressure, Try burnout in second gear and rail pressure drops to 3k psi when floored. .



When driving down the road with about 15percent throttle it will hold 15k psi anything past about 1/2 to full throttle rail pressure will fall to 3k psi . .

 

[Scrappy]

I just have Flux 2,s I have Fass150 my supply psi Stays constant 15psi. .



I think the cp3 is just not putting out enough when its under a load,, I can do a burnout in first gear and it will hold 15k psi rail pressure, Try burnout in second gear and rail pressure drops to 3k psi when floored. .



When driving down the road with about 15percent throttle it will hold 15k psi anything past about 1/2 to full throttle rail pressure will fall to 3k psi . .

uh oh! I just ordered a set of Flux 2. 5's and basically have the same mods as you, I really hope you are wrong! I should know later this week!



I was told that if I keep the TST turned down I "should" be all right, but it does help to have the mp8 working to help get the RP up.

 

[dan shss]

uh oh! I just ordered a set of Flux 2. 5's and basically have the same mods as you, I really hope you are wrong! I should know later this week!



I was told that if I keep the TST turned down I "should" be all right, but it does help to have the mp8 working to help get the RP up.

I have all my boxes unhocked,,maybe i will try and hock up the mp8 and see what happens

 

[hotram03]

Is your injector pump stock?

 

[PBax]

I was having similar RP issues. Low RP across the board and un-steady readings. a week later I developed a knock. atleast 2 injectors were leaking and feeder tubes were clogged.

 

[TCDiesel]

From idle at 4500 to 5200psi shut down engine report what the max spike was,do this 3 to 5 times for correct readings,if no spike bad injectors,if extreme spike clogged tubes, or both. 6k is a little high at idle.

 

[dan shss]

Is your injector pump stock?

Yes cp3 is stock

 

[dan shss]

From idle at 4500 to 5200psi shut down engine report what the max spike was,do this 3 to 5 times for correct readings,if no spike bad injectors,if extreme spike clogged tubes, or both. 6k is a little high at idle.

I will try this and report back.



I had the hole fuel system apart and cleaned so thats not a problem. .

 

[AMassaro]

When you say clogged tubes, can you possibly mean clogged with dirt???

 

[hotram03]

What we need is a sticky for nothing but fuel system test for our CR motors, I think this could help our members SERIOUSLY, it would help alot of people on troubleshooting the CR fuel setup.