How much fuel pressure does the CP3 need? What are you guys using for lift pumps?

[Blacksdieselhp]

I have a 2005 and I was wandering what kind of fuel pressure does the CP3 need to live. I'll more than likely be running a TST PMCR or Edge Hot Juice with a pressure box and an HTT Sledpuller 66. Have you guys tried some different pumps on these trucks? Whats working good?

 

[rbattelle]

CP-3 doesn't technically need any inlet pressure; it needs constant volume. But since volume flow rate is very expensive to measure, most of us are just running a pressure between 9 and 25 psi.



I'm running a Holley blue at the moment (so is JSteiger and lmills). I was running an Aeromotive 11203, but that pump turned out to be incompatible with diesel.



-Ryan

 

[JVolpe]

I have a FASS system. Seemed to be the most popular complete system used by the high horsepower BOMBers. With the HOT Juice and EZ on level 2 sucked the stock LP to 0. Now idles 18psi, with everything in my signature turned up I can drop it to 13psi for a second or so and then it creeps back to 15psi until I let off the throttle. I am happy with the fuel pressure and added filtration level.

 

[Gypsyman]

RASP belt driven mechanical here. Mid 16 psi range 90% of the time never been able to pull it down below 14 psi no matter what stack I was testing. Pictures in my gallery.



Richard

 

[steved]

I have a FASS system. Seemed to be the most popular complete system used by the high horsepower BOMBers. With the HOT Juice and EZ on level 2 sucked the stock LP to 0. Now idles 18psi, with everything in my signature turned up I can drop it to 13psi for a second or so and then it creeps back to 15psi until I let off the throttle. I am happy with the fuel pressure and added filtration level.

I have a FASS system also... It does appear to be one of the most popular "kits" as it is basically a snap together system. I am very pleased with it so far... have about 5k on it already. The only downside is they are somewhat noisey... make sure you listen to one installed in a truck to be sure you can live with it. Mine definately has improved my fuel mileage a bit... not really improved, but made it consistent (see my mods listed in my sig).



steved

 

[JVolpe]

I have a FASS system also... It does appear to be one of the most popular "kits" as it is basically a snap together system. I am very pleased with it so far... have about 5k on it already. The only downside is they are somewhat noisey... make sure you listen to one installed in a truck to be sure you can live with it. Mine definately has improved my fuel mileage a bit... not really improved, but made it consistent (see my mods listed in my sig).



steved

You know I have seen a lot of posts about the FASS being loud. I don't know if it is my hearing(which I do have some hearing loss) or the way it was mounted, I just do not hear mine even standing outside with it running. I have to have the window down to hear it while waiting for squiggly to go out. Maybe it is just me. I know Michael fabbed a bracket and mounted it as high as possible. Anyway I am satisified with the FASS.

 

[Froadin]

Ok, this still doesn't answer the real question though, what is IDEAL for this pump?

I worry about it, and don't turn my box up past 2 just because I don't know what is ideal.

Knowing that 14 psi is ideal for the VP44, and that it wants 45 gph volume, I know what to expect from it. But I don't know this about the new truck yet.



Sorry to hijack the thread, but I have the same question as you, and would like a more precise answer.

Maybe I just need to buy the book for this pump.

 

[steved]

I think that they like very close to 10 psi...



steved

 

[Froadin]

I was just reading that they also like the pressure bumped up under WOT for the guys requiring more fuel?

Not sure at what point that become needed, and how much of a benefit it really is.

 

[JCleary]

You know I have seen a lot of posts about the FASS being loud. I don't know if it is my hearing(which I do have some hearing loss) or the way it was mounted, I just do not hear mine even standing outside with it running. I have to have the window down to hear it while waiting for squiggly to go out. Maybe it is just me. I know Michael fabbed a bracket and mounted it as high as possible. Anyway I am satisified with the FASS.

Ditto on the FASS being quiet. Mine's tucked up far on a customized bracket. I have the 150 with big lines, and I can only hear it when I wait for the grid heater to cycle.



My idle pressure is a solid 20. Haven't turned the boxes up yet to see how far it pulls down, but I'm sure it's not much.

 

[Froadin]

Ok, ao if the inlet fuel pressure is 10 psi CONSTANT, everything is happy? Is that ideal? Ignoring the fact how fuel pumps will vary the pressure/rpm, if the CP3 had 10 psi, it could do just about anything within it's design limits?

 

[mberry]

Froadin,



If the CP3 gets a constant 10psi then yes it could do just about anything within it's design limits as long as it is getting the volume it needs at 10psi. I don't know about ideal. My ideal pressure in my opinion would be 15-18psi constant.

 

[Froadin]

Mberry,

Ok, so what is the volume it needs?



And I am sifting through threads right now to try and answer my own questions.



Thanks

 

[99Supercab]

Pressure doesn`t seem to be the main concern on these engines, volume is the key thing. The dealers don`t even check pressure anymore, they measure volume.

 

[steved]

As we discussed before, a guage is a good indication of volume... to an extent.



A guage going to zero is indicative that you are POTENTIALLY pulling/requiring more fuel than the lift pump can supply. Yes, 10 psi is the rule of thumb... being I have the FASS, I also have the 3/8 line from the tank to CP3 eliminating any restrictions so I unintentionally assume everyone else does too.



steved

 

[cerberusiam]

The Cummins documentation seems to suggest "enough flow to feed the CP3". Go figure. Dig for exacts and get generalities. About the only way that makes sense is if you have the CPL that tells you exactly how much fuel is needed to make the power and size the flow accordingly. Too bad it seems so hard to dig up a relatively simple number for distribution to the masses.



The CP3 works roughly the same way as the VP44 with fuel not used for injection being circulated for cooling and lubing. It will also pull fuel from circ and cooling to feed the demands of the system so it is sensitive to good flow. Best guess seems to be 10 to 15 psi constant and a minmum of 45 to 50 gph for a stock and/or mild performance upgrades. You start BOMBing heavy and flow must go up. It seems the slock LP at 6 to 8 psi is enough to keep the stock system happy, but, add a box and its pretty easy to run the rail dry. It seems a pretty safe bet that providing the same pressure and flow that kept the VP happy will work on the CP3 also.

 

[steved]

I think they "determined" that at max burn you use 15 gph and return 30 gph to the tank (cooling/lubricant).



steved

 

[Froadin]

ok, so the same 15/30 rule as the VP44. But these trucks make more power, so one would think more volume.

I am planning on upgrading the system on the new truck, but I don't want to waste any extra volume/pressure because it basically creates more heat in the fuel. So I am working on the IDEALS, and I will make those happen.

Pretty soon I will have to start calling the shops that modify the CP3's and see what they say their's require (planning for the future ).



Thanks guys, it just seems like this info is hard to come by for the new fuel systems.

 

[ROGER/DODGER]

On the 06 truck if you put the Fass system on it what o you do about the lift pump in the tank? Isn't it a restriction to the new pump or does it have to go also?

 

[EB]

That is the question I want to know also. I just had the pump replaced and the new pump is in the tank. Is it a restriction for a Fass pump? If so, do you need to pull the stock pump completely out, or will it work with it in place.