6.7 fuel pressure at cp3

[scubieman]

Just kind of wondering what red light or too low of fuel pressure would be for 6.7. I know factory specs is 11.5 and I'm normally about ten. But I know 3rd gen I believe that 10 psi is way too low. I think they have the VP pump, unsure.

[Mopar1973Man]

If factory low limit is 11.5 PSI I would get a light that was slightly above this or use a adjustable Hobbs switch.Like on the VP44 (which is a different animal I know) book limit is 10 PSI but the overflow starts closing at 14 PSI so actually the cooling function of the VP44 is reduced getting down to 10 PSI. Now as for the CP3 I know they have a overflow valve as well but unknown to me what the open/close pressures are...

[scubieman]

Well I think high/ regular is 11.5. I just know too little pressure is bad.

[Mopar1973Man]

:think:Personally I don't think its too high really. Little extra pressure keeping return flow is a good thing but carried away with pressure and adding like 20-25 PSI way over kill. (VP44 think again).Now once again I'm short on inofrmation about the 6.7L CP3 ands it overflow valve and such...

[scubieman]

I'm more worried about too low.If you need more info about 6.7 I have owners maintenance manual

[Mopar1973Man]

Well if the minimum is 11.5 PSI so being +5 over 11.5 isn't going to hurt at all consider it reserve pressure. I'm going to assume that CP3 relies on a certain amount of return fuel for cooling and lubing purpose since I know they do have a overflow valve. So if you could look up the open and close pressure of the CP3 overflow valve would help figure out what is actual needed...

[scubieman]

Thanks.

[AH64ID]

Where did you find 11.5 psi? The intank pump is regulated at ~8psi. The Bosch specs for the CP3 are -5 to +15 psi, with 2-12 being optimal. The CP3, unlike the VP44, could really care less about pressure it needs flow! Because of the above limits a light on a CR system is really a waste of money as it doesn't tell you much at all. A gauge isn't much more money and tells you a LOT more. I idle at about 9, cruise at about 7 and pull hills at 6, and can dip below 5 at WOT and above 2700 rpms at 400 rwhp with 3 filters in line.