FPR Vacuum?

[PKRWUD]

It's very necessary. The vacuum is what determines the final fuel pressure. When you are at WOT, there is no manifold vacuum, so the spring inside the FPR opens up the diaphram all the way, allowing maximum fuel pressure. When you back off the throttle, the manifold vacuum rises, and creates resistance against the spring, reducing the fuel pressure. Afterall, when you're backing off the throttle, you want lower pressure. If your friend has no vacuum applied to the FPR, then the pressure will be too high.

I'm surprised the smoke coming from his turndowns wasn't black. Check his oil, and smell the end of the dipstick. It'll smell like gas. His bearings are being eaten away, and his rings aren't sealing. Basically, he's killing his engine rather quickly.

Take care,
~Chris