CP3 Life Expectancy?

[Sacker]

What is the life expectancy of a factory CP3?

I have 106k miles on mine, and it is dropping RP under load.

I have good RP (7,500 psi) at idle, and it seems to be decent when everything is cold, but after warm-up, at 80mph/2k rpm, actual RP will be 2,000-2,500 less than the desired RP according to MM3.

The difference can be as much as 9-10k psi if I hammer on it.

At 100k miles, I did a II short block, different turbo, slightly bigger injectors, trans, changed tuning from Mini Max to DRD, Airdog 165, and added II Bag O Parts.

I never monitored RP before the MM3, so perhaps the CP3 was getting weak.

I have been pretty religious about using fuel treatment, so I thought a CP3 would last longer than 100K miles.

Any info is appreciated.

Thanks, guys!

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[TexNeck]

What is the life expectancy of a factory CP3?

I have 106k miles on mine, and it is dropping RP under load.

I have good RP (7,500 psi) at idle, and it seems to be decent when everything is cold, but after warm-up, at 80mph/2k rpm, actual RP will be 2,000-2,500 less than the desired RP according to MM3.

The difference can be as much as 9-10k psi if I hammer on it.

At 100k miles, I did a II short block, different turbo, slightly bigger injectors, trans, changed tuning from Mini Max to DRD, Airdog 165, and added II Bag O Parts.

I never monitored RP before the MM3, so perhaps the CP3 was getting weak.

I have been pretty religious about using fuel treatment, so I thought a CP3 would last longer than 100K miles.

Any info is appreciated.

Thanks, guys!

Rarely do they go bad. +/- 2k isnt bad if you are in the 20kpsi + range since the relief valve will open.

9-10k is not normal. Is this like a slight lag or does it stay that way when trying to throttle up?

The FCA (Fuel Control Actuator) can go bad which is held onto the pump w 3 torx screws.

To test is start the truck.

Unplug the FCA and you should hear an audible difference (your rail pressure should peg).

If you can have someone look at rail pressure to make sure its in the 22kpsi region.

The replug as quick as you can try and keep it less than 10-20 seconds since it is hard on your injection system.

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[Sacker]

Rarely do they go bad. +/- 2k isnt bad if you are in the 20kpsi + range since the relief valve will open.

9-10k is not normal. Is this like a slight lag or does it stay that way when trying to throttle up?

The FCA (Fuel Control Actuator) can go bad which is held onto the pump w 3 torx screws.

To test is start the truck.

Unplug the FCA and you should hear an audible difference (your rail pressure should peg).

If you can have someone look at rail pressure to make sure its in the 22kpsi region.

The replug as quick as you can try and keep it less than 10-20 seconds since it is hard on your injection system.

The difference between desired RP and actual RP is consistently low.

How low depends on load.

I will test the FCA and see what I find out.

Thank you.

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[Lift89]

Or your stock CP3 can't keep up with the larger injectors and turbo.

A Lift pump will only do so much, you need a CP3 that can push more fuel for that setup, or your FCA might be going out.

I'd start with FCA, and then if that doesn't fix it, I'd assume your CP3 just can't keep up.

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[Bpbertolacini]

Perhaps check your fuel rail relief valve could be weak and opens up at high psi.

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[Sacker]

Ok, so I finally had a chance to check the FCA.

I Unplugged it while idling, and it didn't make as much noise as I anticipated.

RP peaked at 16,900 PSI.

This is odd because I was driving it earlier in the day, and RP peaked at 19,380 actual vs. 27,350 desired.

I will change my lift pump filters only because the truck sat for 18 months while I was doing the overhaul.

Perhaps there was some degraded fuel?

If that doesn't solve the problem, look like a CP3 is in order?

I will stick the factory fuel relief back in the check, but otherwise, I will lose.

I hope it's not the CP3 because I'm getting tired of putting money into it, but I also want it to be correct.

Thanks for all your help, gentlemen.
Steve

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[AK Bob]

Ok, so I finally had a chance to check the FCA.

I Unplugged it while idling, and it didn't make as much noise as I anticipated.

RP peaked at 16,900 PSI.

This is odd because I was driving it earlier in the day, and RP peaked at 19,380 actual vs. 27,350 desired.

I will change my lift pump filters only because the truck sat for 18 months while I was doing the overhaul.

Perhaps there was some degraded fuel?

If that doesn't solve the problem, look like a CP3 is in order?

I will stick the factory fuel relief back in the check, but otherwise, I will lose.

I hope it's not the CP3 because I'm getting tired of putting money into it, but I also want it to be correct.

Thanks for all your help, gentlemen.
Steve

I would replace the FCA next; it sounds like it may be sticking.

With the FCA unplugged, you should be seeing maximum fuel pressure.

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[TexNeck]

I would replace the FCA next; it sounds like it may be sticking.

With the FCA unplugged, you should be seeing maximum fuel pressure.

@Sacker I agree with above.

It sounds like your relief valve may be acting up, so you are not getting consistent high-pressure readings.

If you can buy direct from Cummins.

The last time I checked they were about $80 cheaper than the local dealership.

FYI - The Torx can be a booger to get out to replace it but its about the most straightforward install on the entire truck (1 plug and 3 screws).

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[AK Bob]

When replacing the FCA, I recommend cleaning all around that area with brake clean and compressed air first.

This will help to prevent any contamination from entering the pump.

Unplug, remove the bolts, and rotate both ways as you pull it out.

Do not pry the FCA out. With the old FCA removed, check for any signs of rust or debris.

If there is any metal debris, you may be looking at a new pump.

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[Basskicker]

What is the life expectancy of a factory CP3?

I have 106k miles on mine, and it is dropping RP under load.

I have good RP (7,500 psi) at idle, and it seems to be decent when everything is cold, but after warm-up, at 80mph/2k rpm, actual RP will be 2,000-2,500 less than the desired RP according to MM3.

The difference can be as much as 9-10k psi if I hammer on it.

At 100k miles, I did a II short block, different turbo, slightly bigger injectors, trans, changed tuning from Mini Max to DRD, Airdog 165, and added II Bag O Parts.

I never monitored RP before the MM3, so perhaps the CP3 was getting weak.

I have been pretty religious about using fuel treatment, so I thought a CP3 would last longer than 100K miles.

Any info is appreciated.

Thanks, guys!

Any updates, I'm having similar issues.

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