Fuel pressure issue

turtle64b

The pressure should be set with the reference line (air line from the manifold to the regulator) disconnected. Manifold pressure with the car warm should be about 22in vacuum (-22 on my pressure meter). I notice that when I start my car in the mornings, vacuum starts out around 12-14in vacuum. This leads to pressure being lower than the set 52psi with the line open to atmosphere.

Not trying to be facetious or anything, setting of the reference at atmospheric pressure and the reason for the manifold tap are to ensure that fuel pressure is always the same relative to manifold pressure. Again, I'm not saying that you don't know this, just for anyone who might read this and not know why that line is there.

With your Nismo, the reference could have been set up incorrectly or differently at the recommendation of a different tuner. Seb told me 52psi at idle with the line disconnected. Then reconnect the line and all was good. Perhaps someone either wanted a higher pressure or set the reference at idle with the line connected to the manifold.

I hope this helps, I will look at my regulator pressure when I get home to see what it reads.