III GEN High Pressure Pump Failure due to fuel pressure

[Yo Hoot]

The CP3 high pressure pump on the common rail Cummins is NOT the VP44.



This injection system is a totally different animal.



Has anyone reported high pressure pump failure due to low or lack of fuel pressure... . or to be more specific, is there a trend like with the old VP44 that shows the CP3 failing at a higher rate after a lift pump fails?



I posted the following on another site and would like someone to dig into what I said and let me know how "you really feel"

"Lack of fuel pressure will hurt the power and may cause damage to the CP3 pump. "



I really don't think they can back that up. But maybe they sell lift pumps or are planning to? But to decifer that statement a little more...



"don't drive it hard enough to pull the pressure down below 6psi. "



tells me something is fishy in his knowledge of the CP3 pump. It is designed to operate at zero pressure. It has it's own internal lift pump. and can suck fuel on it's own if the lines were designed to allow it.



Will low pressure effect performance? I think only if supply is restricted. The CP3 can drop pump pressure to zero even when it is fully supplied. The problem occurs when it tries sucking fuel out of a failing lift pump. Fortunately it has a pretty robust gear rotor lift pump that I believe can handle fuel starvation from a cavitation point of view but I don't think the hp pump will run dry. Once pressure drops too far at the rails the truck will shut down and throw a code most likely. Even no pressure in the rails doesn't mean it's dry.



The older Bosch pump P7100 was oil lubricated but the VP44 used on the 24V engines before common rail were fuel lubed and cooled. They are sensitive to unhealthy fuel flow.



The Duramax pretty much has proved out the CP3 is not susceptible to this reduced pressure damage. The Duramax has NO lift pump... it sucks fuel all the way from the tank. People are installing 2 micron fuel filters in the suction path and running stacked boxes... . all creating major vacuum in the fuel system and starving the pump. On top of that people get clogged OEM filters, air leaks in the fuel system that cause hard starting, both because they are starving the pump of fuel.



Not sure what else we need to know unless the Dodge lift pump spews parts into the pump but I think its pre-filter.



I think a lot of guys are using the problems with the VP44 and it's fuel sarvation issues as fuel for these threads, not realizing we are dealing with an entirely different injection pump and fuel system. The CP3 pump is super simple. All it does is pump. It has no distributor rotor. and very few moving parts. Part of the beauty of common rail is the reduced mechanical complexity up until the injector.



Look at the Powerstrokes... . to go off on a tangent. They don't have a fuel injection pump at all. Part of the reason their system is as reliable as it is.

 

[nickleinonen]

does the dmax have larger fuel lines going from the tank to the filters/cp3? the fuel volume is what is important here. if the lines are smaller, you can cheat by upping the pressure with an external lift pump. iirc, the only reason we have the lift pump is to keep "the consumer" from having to manually prime the system after a filter change out... now if we had something like a -8 or -10 [1/2" or 5/8"] line feeding from the tank to the cp3 with a volume pump back near/in the tank, that would clear a lot of fuel problems i think... [bigger is better, right ]

 

[Buffalo]

Yoo-Hoot, I have a buddy with a new Duramax that keeps insisting that the Dodge/Cummins trucks with the Fleetguard 10 Micron fuel filters are, possibly, in for fuel system failure's because 10 Microns is not enough filtration. What are Your'e thoughts regarding this subject and do You have any recommendations as to what Micron level we should be filtering our fuel at? Are there any aftermarket fuel filteration systems, out there, that You are impressed with? Thank You. Joe F.

 

[Yo Hoot]

Yes the Dmax as 1/2" lines which allows it to suck plenty. Again... they have no lift pump and in stock form run under negative pressure at the feed.



Fuel filters...



Yes 2 micron is resommended after some studies were done by Catipallar into the effects of particle sizes in new high pressure fuel systems. I think the truck and engine manufacturers bean counters have it figured out to last until it's out of warranty... no more.



The problem with the Dodge is you need a lift pump to replace the junk Dodge gives you cause a 2 micron filter will add restriction and most likely reduce the life of an already short lif pump. I had a Racor R90S on my Dmax, post OEM filter. Think about it, that hp pump had to suck fuel all the way from the tank in the rear and through 2 fuel filters. Worked great.



I like the FASS system. I need to test one. They allow you to use many different brands of filters and have a very good integrated pump.



FASS system allows the use of these filters...

CIM-TEK 70032 10 Microglass

CIM-TEK 70213 3 Microglass

Fleetguard HF6338 10 Microglass

Fleetguard HF6601 10 Cellulose/Synthetic

Fleetguard HF6610 16 Cellulose

Fleetguard HF6613 12 Microglass

Fleetguard HF6607 6 Microglass

Fleetguard HF6604 3 Microglass

Baldwin BT372-10 20 Cellulose

Baldwin BT372-MPG 12 Microglass

 

[WPeschel]

check out MY ENGINE DIED by EB

 

[Yo Hoot]

Right now I read eb as having a bad hp pump. He ASSUMES it could be because of low feed but I have been reading too many people making assumptions based on GENII VP44 posts.



We all would like to know if lift pump failures are causing hp pump failures for sure. At least is anyone showing hp pumps failing after having lift pumps replaced. Please if anybody has any specific questions re-read my first post in this topic.



His problem is what got me going on this topic. Dodge is delivering it's third model year with the electric lift pump and the new Bosch common rail setup. Is there a rash of hp pump failures like there are with the VP44 of Gen II fame... ??



One failed hp pump and assumptions as to why does not indicate a trend.





2004 2500 4x4, QC SB SLT, HO 305/555, 48RE

Hummer Wheels W/ LT315/70R17 BFG's, Gutted Intake Tube/Silencer Ring AWOL, 5" RIP Straight Pipe 6" SS TIP, Mag-Hytec Rear Cover, K3LA Locomotive Horn



2004 DODGE PICS AND INFO



Had a Duramax

2001 GMC DURAMAX/ALLISON PICS & INFO

 

[DCaswell]

My lift pump failed & less than 6 k later HP pump was gone. Good thing is that any parts replaced by dealer have one year unlimited mileage warranty which is lots better than factory warranty for us high milers

 

[rbattelle]

It's no secret that common rail systems are far more susceptible to wear at the needle and seat than jerk-pump arrangements. I agree that the 3rd gen trucks might be headed for the same injector troubles that the D-Max has, unless these particular Bosch injectors have a different hardening at the tip. I have tried 6 times to email Bosch and ask them what they've done to address this issue, and have never received any response whatsoever.



The real bugger is I don't want to put in a FASS until my warranty is up, because I fear any fuel system trouble following that installation will not be warrantable. But as soon as I hit 100k I'm putting something on there, preferrably in the 2-micron range.