Picking up on Kyle's transducer pressure differential explanation, I suspect
the static air pressure between the engine and the firewall may increase as
the nose is raised from level flight. This could be caused by ram air
entering the bottom of the cowling just forward of the firewall. No actual
altitude change would be needed.


"Aaron Coolidge" wrote in message
...
Roy Page wrote:
: I bought our Piper Archer [PA28-181] just over a year ago from a
Californian
: owner and flew it home to it's new base in Ohio.
: On the flight home, we noticed on long climbs that the fuel pressure
fell
: off from an indicated mid scale reading to about one third scale.

This has always happened on my PA-28-180 as well. It is more noticable in
hot weather. As long as there is positive pressure to the carb there
should
be no problems.

--
Aaron C.