Ok, so I just recently bought a 90 RS that has a 355TPI. I noticed it had a BBK adjustable regulator. I have no instructions, and search didn't help, but I was wondering which way do I turn for it to lower pressure? I took the car on the dyno and it was running about 43 psi and my AFR were sitting at 10:1 or below... so yeah REALLY rich. Would this even be a fuel pressure problem? I didn't think 43 psi was much...

bump... no one knows? I've foudn threads about BBK AFPRs ... but apparently the people have instructions because they talk about lowering and raising the pressure but obviously don't mention how (which way to turn knob)lol

I believe clockwise turns the pressure up. lowering the pressure will NOT change how your car runs (lean/rich), at least it won't change it very much. Higher fuel pressure will not dump more fuel into your engine, the injectors do that. Higher fuel pressure will automize the fuel better.

You need to do some chip/eprom tuning to lean out your car, not change the fuel pressure.

just go ahead and hook up your fuel pressure guage then there will be no doubt. you'll have to have it on anyway. for what it's worth clockwise should up the pressure but with the guage no room for error.

as for rich/lean. i belileve it was in gm high tech under "ram that tpi" where they gained about 20 hp from a fuel pressure adjustment and that adjustment was DROPPING the pressure. the only explanation that comes to mind is leaning out the mix.

uping the pressure doens't always mean more hp. use your af guage and make the adjustments you need.

good luck!!!

Raising it is usually a temporary band aid fix for too small of an injector.