What is it, what does it do? im told now after about 9 months of being boosted that hahn has a check valve thats installed in the fuel set up somewhere and it stops vac to the fpr while not under boost??? this makes no sence to me all im running is the fmu 12:1 ratio and a walbro (no check valve) is this something needed or is it just another usless part?
thanks in advance
joe

the only check valve i know of is to bleed off pressure under boost on a sfmu

A check valve is a valve that allows air to travel in one direction but not the other. Try blowing on your PCV valve, then try blowing the other way, only one way will flow. I can't see how this would help the fuel system at all, since the fmu doesn't react to vacuume signals, only positive pressures.

i agree this is why i asked i was dumbfounded when this was brought to me?? i guess if it aint broke dont fix it right? thanks for the response though
joe