Any body running an engine notice that or is it just
my RV4? Also the mixture is rapidly varying which of course
could be caused by the rapidly changing fuel
pressure. My pressure regulator is referenced to intake
manifold pressure. Is everybody doing that?

It is so bad I can't believe the engine runs.
Now that I have learned to steer the RV I can focus
on what is going on with the engine :)

Paul Lamar


Paul, here are a couple of plots from recent flights,

The 1 psi pressure variation is probably an artifact from the sensitivity of
the logging software.



Bill Schertz
KIS Cruiser #4045
N343BS
Phase one testing Completed

Great work Bill. Thanks for sharing that.
What are you using for data logging?

Paul Lamar

Paul,
I have the stock fuel rails, with the pulse damper on the primary rail, and I also use the black 350 psi fuel injection hose that is used in automobiles. And I use the oil hole pressure taps for measuring vacuum for the regulator. I don't know what kind of fuel lines you are using firewall for ward, but if you don't have a pulse damper and you have very little elasticity in your fuel lines, that might be creating your wildly fluctuating fuel pressures.

My tuning issues were more due to the CAS polarity being reversed. In fact, I'd say that was the entire problem. It runs fine now. I use the stock fuel pressure regulator.

Hope you get it sorted out soon.

Brian Trubee


I am working on a mechanical gage off the pressure regulator tap
I can see in the cockpit.

BTW Robin and will be up in Seattle around next Friday. Robin and I could stop
in and see your RV4. Send me your phone number by private email.
We leave here early Tuesday morning and will be out of touch by
email. I'll send you my cell and robin's cell by private email.

Paul Lamar