Ed, There is one more
thing to think about in your system. Return restriction. If you have a
powerful fuel pump, one that is a bit higher output than the one intended for
the pressure regulator, there may be too much restriction in the return line
to the tank to lower the pressure. The regulator opens the valve, but the pump
overwhelms the ability of the return line to get the fuel back to the
tank.
In the old "dribble" style injectors like the old Hilborne mechanical
systems the top end mixture was set by fuel pressure. A return jet to the tank
was sized backward to normal for mixture. A larger jet lowered the return
pressure and leaned the WOT mixture. Obviously the top was made richer with a
smaller jet. You may have a situation where your return line is like a
smaller jet. Since you are showing higher fuel pressure than Buly the logic
still works. Since your pressure isn't extrodinarily high and you injectors
are time rather than pressure based your system would still run fine. So long
as the pressure wasn't so high as to prevent the injectors from closing the
engine would run OK. Hope this might help.
Bill Jepson
I agree with your assessment, Bill. I
found the specs on the Pressure regulator and they state it flows 8 - 10.5
GPH. I assume that is referring to return flow. Which brings up
the question if my pump puts out 45 GPH at 40 psi it would seem that a return
flow of 10.5 GPH might be inadequate to regulate pressure - but, I am not
certain how much effect on pressure that flow would have. I know that
with no-flow (no pressure regulator) the pressure goes up to 80 psi - so does
the return flow of 10.5 gph represent that required to bring it down to my
nominal 40 psi? Don't know.
Your assessment, plus Rusty's observation that
the pressure regulator might only respond to positive boost pressure might
well be on the money. I do know that the turbo version is simply the
non-reference version with a screw/tube which is connected to manifold hose,
so it might not be responding to low manifold pressures as expected.
I think the only way to go is to try a different
brand - perhaps one like Bullents that does appear to respond to different
manifold pressure.
OR simply keep on flying as I have for the past
260+ hours {:>)
Appreciate you insight
Ed A