THe b&M fuel pressure regualtor is only a fp riser Correct. That would explain why when I set my fp to 43 at idle, the next day its at almost 70? This has happened numerous times. So if I get the aem unit, it should hold the fp to 43 at idle?

 

yep correct the B&M is a fuel pressure riser.
the aem will allow you to adjust your fuel pressure up and down

 

thanks

 

The B&M is nothing more than an adjusting device that clamps on top of the "STOCK" fpr to provide pressure adjustment "up and down". You need to cut the top off the stock fpr and clamp the B&M on, as well as replacing the internal pressure spring. It's NOT a fuel pressure riser that normally associate with other FMU that raises much higher fuel pressure proportional to boost. However, the stock fpr does increase fuel pressure slightly (approx. 1:1) bases on boost pressure.

 

He wasn't thinking that it was a boost dependent fpr. Fmu's and fpr are tow different things. Lie you said one is boost dependent and the other is used to control idle fuel pressure and to provide more fuel (10psi worth) under full throttle.