I just attached a fuel pressure gauge on my 89 7.4 with after-market EFI (Commander pro).
for those of you who know better, should the pressure be constant on the fuel rail?
I attached the pressure gauge direct (removed Schrader valve and installed pressure gauge) and it bounces between 25 and 55 or so, and averages about 35-40. It bounces very fast (10 times/second) regardless of RPM. I am thinking I may need to replace my pressure regulator because of this bouncing, and because it is supposed to be about 45 lbs. But I don't have anything to compare it to...
Thanks for the help.