ERAUMAZDA

When running 720cc x 4 and a walbro is it needed to upgrade the fpr?

NZConvertible

Unlikely. Remember the FPR works a bit like a turbo's wastegate. If it's too small you get too much fuel pressure because it can't get fuel out of the rail fast enough. It doesn't restrict fuel flow into the engine; quite the opposite. It needs to be replaced if you can't keep a constant pressure differential between the fuel rail and the manifold.

ERAUMAZDA

Well, I have read in other threads that the walbro over rates the PSI of the stock FPR. I guess the stock FPR is rated up to 45 psi.

ERAUMAZDA

Information reguarding Fuel pressure regulating is quite poor on the fourm. That or I am not looking hard enough.

Gene

iTrader: (1)

Put it this way, you won't be sorry if you got a good FPR. It sounds like you're shooting for some good power with that setup, so why do things halfway?

ERAUMAZDA

I am looking for 290 ~ 300 at the wheel. I also want to stay away from maxing out the injectors

Rxmfn7

iTrader: (4)

Could someone give an write-up or a quick walkthrough of how an aftermarket FPR is set up? Is the stock FPR bypassed? This is actually one thing Im quite unsure of..

Rxmfn7

iTrader: (4)

scathcart

You remove the stock FPR, and plumb the aftermarket FPR in its place. Not all that hard.

T2 Tsunami

iTrader: (3)

So when exactly is a FPR actually needed?, at what point of mods should you have one?

jacobcartmill

iTrader: (6)

RETed had some illustration of a parallel fuel setup with an FPR. i'll have to post it when i get home (i think his site is down)

jacobcartmill

iTrader: (6)

thats a good question.. i need to acquire some knowledge about FPR's myself cause i really dont even know why you need them.

don't they limit the fuel pressure at the fuel rail so too much/too little fuel doesnt get to the injectors?

lacycw

Here's a good description of how a FPR works for anyone wanting to know.

- Cooper Lacy



(from the Megasquirt website)

ERAUMAZDA

I think with the walbros, so much fuel is pumped in that the spring is pegged.