Hi all,
This is a WK CRD Question. I know this is the forum for the KJ CRD but I'm at a loss and don't know what to troubleshoot on my wife's GC CRD. This forum is tops when it comes to knowledge and I hoping a KJ CRD dieselhead can steer me in the right direction.

Here is my issue: In tank fuel pump makes a loud whining noise..its changes in "tempo" and volume with changes in engine speed/accelerator pedal position

Here is what I've done to date:

(1) Ruled out fuel pump. My wife and I replaced it twice with new "remanufactured" dealer provided fuel pump.
(2) Ruled out obstruction in fuel line feeding the fuel filter...I blew it out with 50psi of air
(3) Replaced fuel filter twice!
(4) Disconnected return fuel line while engine was running...there was return flow but not what I expected..the factory fuel pump flows >100gph at 60psi and I was expecting a stream stronger than an elderly man with prostrate issues! There was a stream and I thought it was a little weak on return flow but dont know what return flow should be at idle volume wise (anybody know?????)

Vehicle runs fine and has full power but we haven't driven it in a month while trying to figure out what is going on. A local dealer mechanic said he feels something is obstructing fuel flow and there must be a clog somewhere.

Any ideas? Would appreciate some suggestions from the diesel/CP3 experts on this forum.

Parts on order:

CP3 MPROP (also called a fuel control valve) The cost to replace this is cheaper than $129/hr labor rate I'd get charged by a dealership to diagnose this issue. Having a spare is not a bad idea but I don't think this is the problem (comments appreciated).

New Spare fuel rail with new regulator valve i (I ordered new one on the internet for $86.....I can't believe I got a $999 part for less than a $100 bucks but I'm not complaining and am grateful the big guy upstairs is looking out for me) I got it from a buyer/reseller who bought out a closed dealership parts inventory and didn't know what he had. I've read that if there is no fuel coming out of the rail return valve line, then it is good and the fuel rail or presure control valve on it shouldn't be replaced.


ANY IDEAS WHAT THIS COULD BE?

Could it be a the cascade overflow valve and can that be replaced or do I need a new CP3 pump.

Thanks!!!!!

Suggest you post this question in the Ausjeep forum in the Grand Cherokee section, should find extensive Grand CRD knowledge there.

Thanks, I will. Based on my reading, I'm thinking my issue is a bad cascade overflow valve. Now I have to figure out how to acquire a replacement instead of replacing the entire pump.

If anyone knows of a vendor that is able to sell Bosch CP3 individual parts, please holler!

Take care all!

Drew

If anybody cares, I fixed my problem. I bought a replacement CP3 and she's good as new. I messed around a bit and put the cascade overflow valve from the new CP3 into the old CP3 and that resolved the problem. I found a vendor who will sell me a new cascade overflow valve so I'll now have a spare CP3 for my WK CRD.

Its been a great experience; I learned all there is about modern diesel fuel systems. I also picked up a brand new mercedes benz fuel rail (dealer price $999) with a regulator valve for $86 from Ebay from a reseller who obviously didn't know what he had. I now have a spare fuel rail, 2 spare MPROPS, and a good CP3 if I ever should need it.

If you curious what a cascade overflow does, here's a little info. It has 3 purposes:

- regulation of lubrication fuel to the internal moving parts of the high-pressure pump
- regulation of the fuel pressure being supplied to the Fuel Control Actuator solenoid valve
- return excess fuel to the fuel tank

My COV failed and was not returning excess fuel in sufficient quantity back to the fuel tank. In tank pump flows about 90gph at 60psi and with vehicle at idle (engine consumes <2 gph idling), return fuel flow was about 1/2 gallon per minute. A lot of strain for the in tank pump resulting it in squealing like a pig. I'm told that at idle,98% of fuel should be returned back to the fuel tank.

I wish our KJ CP3s were as easy to work on. 15 minutes to remove and 20 minutes to reinstall-3 bolts, 2 fuel lines, and 2 electrical plugs.

glad you fixed it - but it sounds like an expensive lesson.

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2005 CRD
stuff
Skeptic quod gratis asseritur, gratis negatur

No, expensive would have been if I took it to a dealership. Without a MIL code, they would have done what I did, replace parts.

Post deleted! Just realized you are talking about another vehicle!

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05CRD: GDE Hot ECU & TCM tunes, Provent, Cat filter, Facet lift pump, TransGo kit, Florida TC, Samcos, stainless brake lines, HDS thermostat, Renegade light bar,
RL super sliders, Bilstein adjustables, Al's Gen 4.5 Arms, 235/85-16 Duratracs, DTT rear, Elocker front, EVIC+TPMS, Turbo timer, McNally pillar gauges, Weeks Stage II kit.

Cat,
Yes, another vehicle but similar fuel delivery system.

Right, minus the in tank pump at 60psi! That was a little shocking to read.

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05CRD: GDE Hot ECU & TCM tunes, Provent, Cat filter, Facet lift pump, TransGo kit, Florida TC, Samcos, stainless brake lines, HDS thermostat, Renegade light bar,
RL super sliders, Bilstein adjustables, Al's Gen 4.5 Arms, 235/85-16 Duratracs, DTT rear, Elocker front, EVIC+TPMS, Turbo timer, McNally pillar gauges, Weeks Stage II kit.