Installing AFPR
 

I recently installed a turbo kit in my '96 miata. I changed the stock fuel pump with a fuel pump from a RX7. The only problem i'm having no that the engine is to lean, and i don't know if it's because of mine APFR i installed. I installed it between the fuel rail and the fuel feed line, but the stock fpr is still installed, because when i took it off the fuel rail, it didn't even start. Does anybody know what i did wrong or what i need to fix??? thanks in advance :)

you're effectively reducing the amount of fuel your injector are getting when in boost.

I suggest you read our "all you answer in one big post" thread in the used saved posts section.

What you did wrong is just before where you ask what you did wrong.

Fuel pressure regulators work by causing a restriction to the flow of fuel through them.

In a recirculating fuel system, any fuel pressure regulator must therefore be installed after the fuel rail, between it and the return line.

If you install any fuel pressure regulator between the fuel rail and the supply line, then the regulator will cause fuel pressure at the rail to decrease as the regulator's reference signal rises.

The correct scheme for installing an AFPR on a '90-'97 Miata is:

Supply line -> fuel rail -> stock FPR -> AFPR -> return line.

but don't i need to eliminate the stock FPR? because if i put the AFPR after the stock FPR isn't it useless of having a AFPR??

only if you want to lower the fuel pressure below stock...

read my faq. stop doubting.