I was using my stock fpr with 440's controlled by the ultimate emanage and my partial throttle was terrible. My idle a/f was terribly inconsistant and the car would lean out to the point it would buck on gradual acceleration. My stock fpr was giving my static fuel pressure of 58psi and idle was at 54psi. As soon as you would go higher than idle, the fuel pressure would actually drop and then pan out once the rpm steadied.

I put on the AEM fpr last night and set it to 57psi static. It has made a drastic change in my partial throttle. The car feels just as good as it did when it was stock in the low rpm/low throttle position. The warm-up a/f is now 13.5-14 and the idle is back where it should be. I am so happy I cannot even explain it. I am wondering if my stock fpr just couldn't handle the increased pressure of the walbro?

 

i don't think the stock frp had a good tunning window that you needed.