Dennis,
Help me
out here. If you’re taking fuel pressure from the spider, where are you
measuring fuel flow? How can you determine a constant fuel pressure when the
pressure at the spider varies with throttle position? Are you truly measuring
FF with a flow transducer or a pressure transducer?
Every
other electronic engine monitor I’ve seen that uses a flow transducer for
FF mounts between the servo and the spider. All the fuel going to the spider
has to spin the turbine wheel.
-----Original Message-----
From: Lancair Mailing List
[mailto:lml@lancaironline.net] On Behalf Of Dennis
Johnson
Sent: Wednesday, April 14, 2010
2:31 PM
To: lml@lancaironline.net
Subject: [LML] Re: Fuel Pressure
Setup
I set up my Legacy IO-550 the same way as you. I
measure metered fuel pressure at the fuel spider. I did that because it
seemed like it would give me more useful information and also because the
Chelton installation instructions recommended it. It may also make doing
the required fuel flow and pressure adjustments a little easier because I think
the metered pressure is more important than the unmetered. On the other
hand, most of the other Legacies are set up to measure unmetered fuel pressure
and that seems to work, too.
I used tiny stainless steel tubing to get from the
fuel spider to a convenient place to connect flexible hose that runs
back to the pressure sensor on the firewall. The fuel spider is fairly
close to the upper cowl and the intake pipes and there's not a lot of extra
room there. I used soft aluminum tube the first time, which cracked at
the fuel spider flared fitting and leaked. No good! So far, no
leaks from the stainless tubing. Here's a photo:
Legacy, 300+ hours, doing my third annual inspection
this month