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Okay techies will it work??

14K views 44 replies 19 participants last post by  Accurate 
#1 ·
#4 ·
Very interesting. I wonder if it would starve the pump of fuel at all because it would be directing some back instead
 
#6 ·
We would be happy to answer (or try to answer!) any questions anyone has on the kit. There is no problem with starving the pump for fuel - remember that there was always fuel return back to the tank, even before the modification. The kit has been extensively tested including while doing some very heavy towing with monitoring of all relevant parameters which proved completely normal.

Thank you for your interest.
 
#7 ·
I'm having trouble understanding the fuel route involved in the HPFP, I haven't been able to find a schematic to help either. I thought the fuel that enters the crankcase is then pulled directly to the inlet of the pump (all one circuit) but for this system to work, the pump would have to be two separate circuits to be able to pull one off and send it back to the tank. Can you shed some light on this @Accurate?
 
#10 ·
Hi!
The concept is pretty simple, although following the circuits through the pump can get tricky. The Metering Unit / FCA (two terminal electrical fuel pressure regulator on top of the pump) controls how much fuel is allowed into the two high pressure pumping chambers, and therefore, ultimately, the rail pressure. In the stock setup, fuel supply to the metering unit first travels through the crankcase of the CP4 pump to keep thing lubricated, then some goes back to the tank, and some to the metering unit. The bypass kit re-arranges things so that the fuel supply to the metering unit comes directly from the truck's fuel tank / electric lift pump / filter.

The crankcase of the pump continues to receive it's own separate supply of fuel for lubrication, only instead of a percentage of the outgoing lubrication fuel now going to the pumping chambers, it all goes back out to return to the tank.

To summarize:

Stock Arrangement - Fuel supply from tank > pump crankcase > metering unit AND return circuit

Bypass kit arrangement has two paths:

Fuel supply from tank > metering unit and on to high pressure pumping elements / rails and injectors
AND
Fuel supply from tank > pump crankcase for lubrication > back to the tank for re-filtering

Hope that helps! I'll post some pictures a bit later.
 
#13 ·
I believe a video is required. Also rail pressures before and after install, at load, at speed.
 
#14 ·
Here are the promised pictures.

The first picture shows the stock configuration of connections at the CP3, nothing changed. Fuel supply line on the left, fuel return line on the right.



The second picture shows the bypass block set in place. Note that the fuel return line is still attached to the pump in the stock location toward the right side of the picture. It was not removed. The metering unit was removed prior to setting the bypass block in place, and has not been reinstalled for this picture.



In the last picture, the metering unit has been reinstalled on top of the block and re-attached. Note the new supply line (metal braided hose) attached to the bypass block. The new supply line feeds the pump where the original supply line was removed and, additionally via a direct passage straight to the metering unit through the block (no passing through the crankcase first).



Regarding the question of rail pressure, the PCM itself is constantly monitoring rail pressure and comparing actual and desired. Any deviation above very tight limits will set a code - trucks do not code with these kits installed, under any conditions. Many tens of thousands of miles have been logged in testing before these kits were released to the public. As long as adequate fuel volume is supplied to the high pressure pumping units, the path it takes in getting there is irrelevant and will not affect rail pressure.
 
#15 ·
I would like to see the commanded vs actual rail pressure in the IDS tool and the GPM actual vs commanded at the Lift pump. All in all it is a sound idea. Only problem i see is extra demand on filters and lift pump. and if some containment gets in it might starve the pumps but still would save the rest of the HPF system.
 
#16 ·
One thing to keep in mind - it's probably ultimately not in our best interest as a fuel injection shop to persuade everyone here that this is the way to go. Eight injectors and a pump plug lines, rails, etc is a nice sale for us :)
Consider this more as a public service announcement....
 
#17 ·
Ok I'm understanding a little better now I think. From drawings/cutaways I've seen it appears the passage from crankcase to the high pressure side is cast into the pump and therefore couldn't be rerouted. But from the sounds of your descriptions and pics thats not true? This is one of the drawings I'm mentioning.

Besides that though, even tho we are saving the rest of the system from shrapnel and contaminates isn't it the water/rust that ultimately condemns the injectors and rails? This setup won't stop that as filters don't catch water, correct?

Edit: sorry for the Russian...
 

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#19 ·
Nice picture! I'll have to see if my phone can translate the captions...

You are correct, the factory feed passage to the MPROP is cast into the pump body. The bypass kit simply blocks that passage off and a new passage is routed right through the bypass block to the MPROP which now sits on top of the bypass block directly above it's old location.

This system is not designed to prevent fuel system failures caused by bad fuel / fuel mixed with water or other contaminants. Its purpose is singularly to prevent the immediate failure of the rest of the injection system when the CP4 pump experiences internal failure - which is, unfortunately, fairly common.

My personal experience with this system has been with otherwise stock (or perhaps lightly modified) trucks. Since modification can occur in many different forms and at many different levels, testing the system with each and every one of those scenarios, would be quite an undertaking - but, again, fundamentally, the high pressure pumping elements don't care if their supply fuel did, or did not, travel through the crankcase of the pump before feeding them.
 
#20 ·
Ok making sense now. Thanks for the explanations! Seems like a viable form of insurance to me haha

Hows the install?? simple hand tools and 30 mins?
 
#22 ·
Is this something fairly new to the 6.7L industry? Seems like no one has heard of this little guy before and judging by the amount of product on your website, you aren't new to the game.
 
#24 ·
#25 ·
We will be glad to put something together. Thank you for getting the ball rolling! No terribly formalized process exists for group buys here! If you would like to assemble a list of interested persons, we will determine what we can offer as far as a discount base on the size of the list and move forward from there.
 
#27 ·
I believe the return line from the pump to tank is not modified from the original stock line so it would be difficult to find a spot for and implement a filter on that line.
 
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