ok, i know the cummins FCA can be modified but i havent had the cajones to chop it up yet.....but my main question is....
does the Dmax FCA flow more fuel than the one for the cummins? I know i heard the Dmax one doesnt like extra input pressure so could you make a hybrid and change out the moving sleeve from ours with the triangle cut in it for the sleeve from the Dmax or just replace the whole thing?
I know this is outta the blue but my wheels are turnin and i am always lookin for somethin new
adam

 

I know exactly what you are talking about. I was wondering the same thing. they have a different name for it in the duramax world, but I was thinking about modding the one in my lb7 chevy, because of what you guys were doing with yours. It would be interesting to do a side by side comparison.

 

Here is the only modification to an fca that i've heard of..

http://relentlessdiesel.com/forum/viewtopic.php?t=19

 

the d-max fca will flow no more than a cummins, but the cummins can handle much more input pressure than a d-max. dont know why but thats the case. the d-max pump it self is supposed to flow more than the cummins though.

 

Do a search. I recall someone doing this CP3 mod and it messed things up.

 

If you take your time and follow the instructions in the thread it will go fine the only trouble anyone has had is not getting the valve smooth enough before reinstalling it and it was a little sticky causing spike in Idleing RPM's once they took them back apart and cleaned them up and polished them like they should have been done in the first place they were fine. I have had no trouble with mine its been on for a month or so.

 

I dont know if it was me or not but I did blow my RV and after I fixed that the end cap came out of my modded FCA. I am sure the mod did not help my RV any but it was on borrowed time any way and though the fca mod may have gotten me there quicker it was gonna blow any way.

The end cap comin out was my fault to some how I am sure.

 

because the FICM/EDU (especially on LB7's) has fuel running through it to keep it cool and doesnt like much more than 10psi of pre-CP3 fue pressure.

LLY's are not as bad; you can run up to ~15psi lift pump pressure with them.

Theres no point running more than 10psi though, IMO. As long as you are not dragging the fuel supply into vacuum at WOT, having more lift pump supply pressure isnt going to help much. Just my oppinion....

ben

 

Please tell me why you know this to be a fact. I really want to know

 

we have tryed it on wades truck both ways!

 

Haven't tried it on my CTD yet. I'll get back to you.

 

is the plunger interchangeable between fcas, or do you have to change the whole assembly?

does a cummins cp3 have an internal lift pump like the duramax?

 

hey smoke_pedal why dont you go ahead and do an experiment for me and put you LB7 CP3 on your cummins or swithc the FCAs and let us know what happens!!

 

I might do that, but I have a 12 valve. Sorry.

 

Actually it is the other way around Ben. LLY's get weird at around 10psi where as the LB7 gets weird at 14 psi. But this can be used at least on a LB7 to our advantage! Can you say 27kpsi!


You are correct about the FICM being the problem not the FCA (Pressure regulator in the Dmax world). The Cummins uses a Bosch ECM which does not need a FICM like the Delphi unit used in 01-05 Dmaxs. 06 Dmaxs do not use a FICM either and could really care less about input pressure from a lift pump.