Electronic Fuel Injection with Master Off

[genna]

How does that actually work?

With a carb, the fuel delivery is mechanical, so no need for electrical power for the mixture to get into the engine. Ignition is powered by magnetos and that's all you need. But with an EFI system, you need a stable electrical power for the ECU. Since the engine continues to run with Master Off, is it running direct of magnetos or does it have some internal battery or what?

 

[Dan Thomas]

How does that actually work?

With a carb, the fuel delivery is mechanical, so no need for electrical power for the mixture to get into the engine. Ignition is powered by magnetos and that's all you need. But with an EFI system, you need a stable electrical power for the ECU. Since the engine continues to run with Master Off, is it running direct of magnetos or does it have some internal battery or what?

Only a few homebuilts, the SMA diesel and the new Lycoming iE2 engine have EFI and an ECU. All other aircraft fuel injection is 100% mechanical and doesn't need electricity (other than the emergency boost pump, of course). The SMA has a mechanical backup if the ECU fails.

Dan

 

[genna]

Only a few homebuilts, the SMA diesel and the new Lycoming iE2 engine have EFI and an ECU. All other aircraft fuel injection is 100% mechanical and doesn't need electricity (other than the emergency boost pump, of course). The SMA has a mechanical backup if the ECU fails.

Dan

Ah.. Never even thought about that. Certainly answers my question.

Thanks

 

[d5by5]

How does that actually work?

With a carb, the fuel delivery is mechanical, so no need for electrical power for the mixture to get into the engine. Ignition is powered by magnetos and that's all you need. But with an EFI system, you need a stable electrical power for the ECU. Since the engine continues to run with Master Off, is it running direct of magnetos or does it have some internal battery or what?

The 'master' switch is for the avionics, not the engine. The 'bat' and 'gen' switches must be on to start the engine. The alternator and battery power the ECU and ignition system as well as the fuel injection pump.

 

[Ravioli]

I have have Lightspeed Plasma electronic ignitions (no mags)

If I have to shut down all electrical there is a "saftety" switch that connects the battery to one ignition directly so it can run till battery failure. Supposedly keeps the prop spinning for 30min or so to find a place to put down. Haven't had to do it yet (thank goodness)

 

[genna]

The 'master' switch is for the avionics, not the engine. The 'bat' and 'gen' switches must be on to start the engine. The alternator and battery power the ECU and ignition system as well as the fuel injection pump.

Actually, on the planes I fly: Cessna. the Bat/Alt switch is the "Master". The Avionics is a separate "Avionics Master". See attachment

Master Bat disconnects everything from the battery, shutting down ALL electrics. And as I stated in original question, the engine does not need it to run because it has magnetos.

Master Alt, disconnects the Alternator/Gen, leaving everything connected to battery, but battery no longer charging.

Avionics Master merely disconnects the panel(or whatever you connect to it)

 

[FastEddieB]

I believe the fuel injection on the new ROTAX 912is is electrical.

I have to assume it's not powered via the master. I know it requires redundant electrical sources for it operation.

The diesel Thielert also had electronic fuel injection, I believe.

 

[flyingron]

The 'master' switch is for the avionics, not the engine. The 'bat' and 'gen' switches must be on to start the engine. The alternator and battery power the ECU and ignition system as well as the fuel injection pump.

The engine starts fine with the GEN switch off (in fact, mine you want the switch off while cranking).

 

[Dan Thomas]

The engine starts fine with the GEN switch off (in fact, mine you want the switch off while cranking).

There are a few weird systems out there that need the ALT switch on when starting. The Aerostar is an example. As originally wired, it relied on the residual magnetism in the rotor of the alternator to bootstrap the field after the ALT switch was turned on after start, and since that rotor's residual magnetism is often insufficient to generate enough voltage to break over the diodes, it didn't work. Aerostar came out with a service kit to install diodes between the starter contactor and voltage regulator, and the engines were started with the ALT switches on.

I can't remember why they didn't just use the bus like they do in most other airplanes. There was a good reason, but it escapes me now...

 

[flyingron]

There are a few weird systems out there that need the ALT switch on when starting. .

Then you don't have a GEN switch, do you?

 

[Dan Thomas]

Then you don't have a GEN switch, do you?

See that! I need to read things a little slower. No, no Gen switch.

Actually, I need to spend a lot less time reading these forums and go out and actually work on my airplane. And fly it.

 

[Hiperbiper]

I am in the process of installing an EFII system in a second airplane (a Velocity), The first was an RV8 that has close to 100 hrs since the install and runs like a Swiss watch!
On the RV (and now the Velocity) I make an "Ignition Buss" consisting of a short buss bar connecting CB's for the ECU(s) and the coils and fed by TWO wires (one attached to each end of the bar) connected directly to the + battery terminal. It then goes to the ignition switches and from those to the ECU/coils. The ignition switches are powered all the time by the battery itself, not thru the master relay.
I also place the CB's in an accessible place to allow for maintenance and immobilization of the aircraft...the RV has them just above the battery and reachable thru the oil fill door!

So far the EFII system seems bullet proof and works quite well.

Chris

 

[unsafervguy]

I have have Lightspeed Plasma electronic ignitions (no mags)

If I have to shut down all electrical there is a "saftety" switch that connects the battery to one ignition directly so it can run till battery failure. Supposedly keeps the prop spinning for 30min or so to find a place to put down. Haven't had to do it yet (thank goodness)

just to give you a better feeling about that.

I had a talk with klaus about the system. the way it is designed, if you load shed everything else and have just the ignition running on the battery you should have a couple of hrs before the ignition sputters.