ducmot

Thanks. That is about what I am experiencing, although a little faster, but through 8-11,000 ft.

Generally, my 1966 M20C has normal fuel pressure on climb-out, cruise, etc. The airport where I fly out of is at 5,000 feet and I have a mountain range to the east that goes up to 10,000 within 15 miles. I have noticed when I am climbing out to higher altitudes to clear the top my fuel pressure will go down to the really small green portion around 2.5psi. It still works fine of course. I haven't tried turning on the boost pump.......especially since there is no noticeable signs of lack of fuel. Does anybody else have this happen on theirs?