Pressure
Registered User
Joined: Jun 2005
Posts: 2,452
Likes: 1
From: Nebraska
The fuel is metered as it enters the pump by the FCA, and rail pressure is read in the rail through the rail pressure sensor. The ECM reads rail pressure and controls the amount of fuel metered by the FCA, therefore despite the pump's capability to flow the ecm can control the amount of fuel pressure in the rail by metering the amount of fuel flowing through the pump. That is why when you plug a pressure box into the rail sensor it is able to alter the RP signal to command more fuel from the FCA.
The RV really has no effect until rail pressure has exceeded the maximum limit and blows through. At cruising speeds it should remain closed. If not, it leaks and should be replaced.
The RV really has no effect until rail pressure has exceeded the maximum limit and blows through. At cruising speeds it should remain closed. If not, it leaks and should be replaced.
Registered User
Joined: Jun 2007
Posts: 341
Likes: 0
From: Alaska
Excess fuel is regulated by the cascade overflow valve (COV) in the CP3. According to design the COV has 3 main functions It regulates internal pump lubrication, it regulates fuel pressure supplied to the Fuel Control Actuator and it controls the return of excess fuel to the tank through the return circuit.
Registered User
Joined: Jun 2005
Posts: 2,452
Likes: 1
From: Nebraska
Excess fuel is regulated by the cascade overflow valve (COV) in the CP3. According to design the COV has 3 main functions It regulates internal pump lubrication, it regulates fuel pressure supplied to the Fuel Control Actuator and it controls the return of excess fuel to the tank through the return circuit.
Registered User
Joined: Jun 2007
Posts: 341
Likes: 0
From: Alaska
I am not really sure how duals are set up on the return, but in the case of the single CP3 the stock return circuit is adequate.
Banned
Joined: May 2006
Posts: 3,660
Likes: 0
From: Florida
Cruising at what speed? The only time I see 17,000 is if I drive 50-60 MPH and we all know how people like to go 55 MPH everywhere they go.
The truth is that guys are seeing 20k cruising on a regular basis with stock pressure programming. I'm pretty sure most guys that have a properly operating CP3 are pushing close to 20,000 at regular highway speeds of 65-75. With close to stock tires and 3:73 gears the engine is turning 2000 RPM at 70 MPH, so most of these trucks are easily at 20K cruising.
If it is truly the case that 20k cruising speeds kill injectors, then we should be on a quest to reduce stock pressure from destroying our injectors.
The truth is that guys are seeing 20k cruising on a regular basis with stock pressure programming. I'm pretty sure most guys that have a properly operating CP3 are pushing close to 20,000 at regular highway speeds of 65-75. With close to stock tires and 3:73 gears the engine is turning 2000 RPM at 70 MPH, so most of these trucks are easily at 20K cruising.
If it is truly the case that 20k cruising speeds kill injectors, then we should be on a quest to reduce stock pressure from destroying our injectors.
I would also like to know how we're expected to keep injectors alive if our truck cruises 75mph at 20k psi with stock programming? If 20k is too much then Dodge/Cummins screwed up pretty bad.
Registered User
Joined: Feb 2004
Posts: 1,244
Likes: 0
From: St. Charles missouri
You pretty much said there was no truth in my statement and that it was pure speculation. Then you said "why listen to somebody that stacks two timing boxes", when you don't know what I run and in what moderations? But it's all right, I don't really care everybody is intitled to thier own oponion.
Registered User
Joined: Dec 2003
Posts: 5,540
Likes: 0
From: Boise, Idaho
NOBODY needs more than 50% of the MP-8...
Monitor your rail pressure...spend the dough for the gauge...its worth every penny for tuning, diagnostics, and just enertainment.
I have run the pressures Don has stated on my 04 for 140k...with NO injector problems.
Monitor your rail pressure...spend the dough for the gauge...its worth every penny for tuning, diagnostics, and just enertainment.
I have run the pressures Don has stated on my 04 for 140k...with NO injector problems.
Registered User
Joined: Aug 2007
Posts: 25
Likes: 0
Cruising at what speed? The only time I see 17,000 is if I drive 50-60 MPH and we all know how people like to go 55 MPH everywhere they go.
The truth is that guys are seeing 20k cruising on a regular basis with stock pressure programming. I'm pretty sure most guys that have a properly operating CP3 are pushing close to 20,000 at regular highway speeds of 65-75. With close to stock tires and 3:73 gears the engine is turning 2000 RPM at 70 MPH, so most of these trucks are easily at 20K cruising.
If it is truly the case that 20k cruising speeds kill injectors, then we should be on a quest to reduce stock pressure from destroying our injectors.
The truth is that guys are seeing 20k cruising on a regular basis with stock pressure programming. I'm pretty sure most guys that have a properly operating CP3 are pushing close to 20,000 at regular highway speeds of 65-75. With close to stock tires and 3:73 gears the engine is turning 2000 RPM at 70 MPH, so most of these trucks are easily at 20K cruising.
If it is truly the case that 20k cruising speeds kill injectors, then we should be on a quest to reduce stock pressure from destroying our injectors.
Registered User
Joined: Jun 2009
Posts: 246
Likes: 0
sorry to bring this one back to life but i didnt see an answer to whether or not complete aftermarket injectors will withstand these higher rail pressures or not. I need to buy injectors this week as my truck is down and that would really help with the decision.
Registered User
Joined: May 2007
Posts: 704
Likes: 2
From: Bellingham, WA
Are you saying to start it with that banjo bolt out? Cause i would sure cap that line or else it will flow return fuel from the cp3 all over the place! Remember fuel on top of the valve doesn't mean its failing because the cp3 return line tee's into the return line connecting the relief valve at the fuel filter hosing before routing back to the tank. So in other words fuel from the cp3 return will flow to the top of the relief valve. You would need to dry out the valve and start it with connecting line capped off to see if the valve is actually leaking. The dealer has a fitting just for that...
Registered User
Joined: Nov 2006
Posts: 1,628
Likes: 1
From: N.C.
Are you saying to start it with that banjo bolt out? Cause i would sure cap that line or else it will flow return fuel from the cp3 all over the place! Remember fuel on top of the valve doesn't mean its failing because the cp3 return line tee's into the return line connecting the relief valve at the fuel filter hosing before routing back to the tank. So in other words fuel from the cp3 return will flow to the top of the relief valve. You would need to dry out the valve and start it with connecting line capped off to see if the valve is actually leaking. The dealer has a fitting just for that...
But a special banjo bolt/plug would be nice! Anyone know the Cummins part #?
Registered User
Joined: May 2007
Posts: 704
Likes: 2
From: Bellingham, WA
When I have done this I just gently push the return line to the side of the relief valve and then zip tie a bag on to catch the fuel.It doesn't take but a couple seconds to verify if the RV is leaking or not.
But a special banjo bolt/plug would be nice! Anyone know the Cummins part #?
But a special banjo bolt/plug would be nice! Anyone know the Cummins part #?
Thread
Thread Starter
Forum
Replies
Last Post
snakefarmer
3rd Gen Engine and Drivetrain -> 2003-2007
8
Jan 3, 2006 05:29 PM
CIN'S DODGE
24 Valve Engine and Drivetrain
16
Dec 5, 2005 04:14 PM
mtl0727
3rd Gen High Performance and Accessories (5.9L Only)
1
Nov 5, 2005 06:47 PM
darrenG
24 Valve Engine and Drivetrain
10
Jun 28, 2005 07:43 AM
Flatty
Performance and Accessories 2nd gen only
1
Jan 5, 2005 02:50 PM