Just had a quick question. I have been trying to find the difference between my aftermarket fuel pressure regulator and and actual FMU(vortech, etc..) I mean if I can adjust my pressure myself then do I need to get another part that adjusts the pressure as well? I am planning on running like 5 psi boost which would equal 60 psi of fuel with the 12:1 ratio. Let me know cuz I would rather suve the 100.00 and buy other parts. Thanks

 

Anyone? This should be easy for anyone that has a turbo on their car?

 

Typically, the stock fuel pressure regulator (on the fuel rail) will regulate fuel pressure from idle (20 inches of vacuum) to atmospheric pressure (0 in/0psi). The FMU will regulate pressure from 0psi to maximum boost.

You need both devices. FMU's (with the exception of the Cartech SFMU) cannot accurately control fuel pressure while the engine is under vacuum (ie, cruising or idle).

Many people get an aftermarket FPR (like the AEM FPR) because the big pump mandated by the FMU often overwhelms the stock FPR such that it can no longer control fuel delivery between idle and 0psi.

Sonny

 

An FPR adjusts your static and vacuum fuel pressure. An FMU adds fuel pressure as boost increases. If you start out with, say, 40psi of fuel pressure at idle, and boos tup to 5lbs, then the 12:1 FMU adds 60psi of fuel pressure on top of the 40psi you started with. An FPR doesn't adjust fuel pressure according to boost. You'll need an inline pump to run an FMU.

 

Awsome, that's what I was looking for. Now either way I was going to get another fuel pump, would an in-tank not work? Do I have to go in-line? Otherwise I was just going to get like a 255-lph in tank pump. Thanks again