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Bill, here is one viewpoint.
Not certain whether you have Tracy's EC2 or plan on getting it, but, in his design he has provisions for two switches (Injector disable) that when on provided 12VDC directly to the injector pairs. If I were doing my again, I would route 12VDC through each switch from a separate battery bus. Tracy's diagram shows both switches tied to the same 12VDC power source, and that is fine and the way mine is wired. However for maximum fall back, if doing it over, I would connect each switch to a separate power source (if you are using two batteries). Same for the ignition modules, each to a separate power source through either a separate switch or circuit breaker - again for redundancy.
While there are different viewpoints about fuses vs circuit breakers, I use only circuit breakers for my critical systems (fuel, ignition, CPU). I do use fuses for none critical circuits - so not against fuses - but they can not be reset. I have had transit surges pop a circuit breaker and was able to reset it. This is My personal view point of course.
For all my critical systems I also wired a 12VDC lead through a 20 amp circuit breaker (normally open) that will provide power around any switches to my critical systems. Should a switch fail (and I have presence of mind), all I have to do is push in the 20 amp circuit breaker and power is routed around any switches in the critical links. Yeah probably overkill, but I just don't want to do another 12 miles glide. I also recommend top quality sealed switches that are used in the critical circuit - this is not the place to pinch pennies. Mine cost around $25 each back a decade ago and so far have withstood the test of time.
As Al mentioned if either of the injector disable switches are turned off if you attempt to put the controller back to its default MAP settings, you will get Tracy Crooks "default" settings because the cold start is engaged when ever either injector switch is off. IF you want the standard default (as opposed to Tracy Crooks default), then the injector disable switches should both be ON when resetting the EC2 to the standard default.
One thing to be aware of, any time power is applied to the injectors, there is a sneak circuit in the EC2 that permits sufficient power to activate the EC2 (without you turning on the power to the EC2). I have one of the older EC2s that has a light in the program store button that lights up whenever the EC2 has power (this is nice). So if you follow Tracy's instructions about holding the program store button and then turning on the Power to reset to default - you must be certain there is not already power to the EC2 already - such as through the injectors and the sneak circuit. Now you may think just turn off the injectors disable switch - and that does remove power through the sneak circuit - but, it also grounds the cold start switch which gives you Tracy's Default value. In my case, I simply remember that turning the injectors on powers up the EC2, so I hold the program store switch in and then turn on both injector disable switches (there by insuring the cold start is not ground), which provides power to the EC2 and gives me the standard default. Probably more than you wanted to know.
Best Regards
Ed
----- Original Message ----- From: "Bill Bradburry" <bbradburry@allvantage.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Thursday, October 19, 2006 11:52 AM
Subject: [FlyRotary] Powering fuel injectors
I am using Z-19 from the Aeroelectric Connection as a guide for wiring
my plane. I would like to power the injectors from the battery buss.
Looking at Z-19, do I need to install a complete switch and diode system
for the injectors like is done for the fuel pump and ECU, or can I tie
on to the fuel pump OR the ECU system after either the switch (add a
separate diode) or after one of the diodes?
There will be the two DPDT switches to disable the primary and secondary
injectors after this connection.
My panel is becoming somewhat switch festooned and I would like to keep
more switches to a minimum.
How have you guys accomplished this?
Thanks.
Bill B
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