Drew, do you know how the CP3 regulates it's pressure? With a pressure box attached, i'd assume it's fooling the PCM into allowing the pressure to build further...does that sound right?

have you seen any pics or diagrams of the fuel flow thru it?

My motivation and curiosity is getting the better of me... is it time to kick the wifes corolla outa the garage for a few days? [sm=badbadbad.gif] projects are backing up (still dont have my guages finished...)

 

It looks as though it is done with a regulator ontop of the far piston, you can see the electrical hookup.

 

lemme drag that pic I posted earlier over here. . . .



if you look at the left hand side of the CP3 you'll see a connector, that is the FCA (Fuel Control Actuator). it works in conjunction with the rail pressure transducer and the computer fuel mappings to limit the pressure the CP3 is putting out. when idleing the computer wants to see around 5000psi, the FCA controls the CP3's overall operation with the only input comeing from the rail pressure transducer. with your foot in the throttle, pushing max boost the rail can see around 23,000psi.

when you put a pressure box on the engine, what the box is doing is showing the rail pressure transducer having a low pressure senerio, so the computer commands the FCA to juice the CP3 up a bit to over come this "low fuel" issue.

this is about as easy as I can make it. . .I know how it works over all, I just dont know the full details without pulling it apart. . .looks like I need to do some research

 

makes sense... however where does the excess go? you mentioned that it is used to cool & lubricate the unit so that would tell me the output line should be hot to the touch after a good run.

 

the excess would just be pushed back to the fuel tank and it should be quite warm

 

Seems like everyone is returning to the tank now. On the older engines is seemed like they always used to return to the filter head or the transfer pump.

 

yup, thus the need for a cooler! now it makes total sense as to why it runs so different in the winter vs summer...

 

another thought... if I crawl under the truck after I get home, I should be able to feel which line is the return line based on how hot the line is... then I could follow it back to the cp3... any idea how much pressure this fuel would be under?

 

Should be a little less than what the lift pump is putting out I would think.

 

there should be a decient flow to it, but just as jake said, it wont have the pressure the feed line has.