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Fuel Return for Injected Engines?

aeroaddict

Well Known Member
Just started to build the fuel tanks and stumbled across a post about the fuel return lines needed for fuel injected engines. I haven't really thought that far forward but plan on using a common experimental (ex-certified) engine with fuel injection. A brief search did not reveal much info.

Is it common for injected engines to have a return?
 
Some do, some dont.

If you install a bung fitting, it can be plugged if you end up not needing it.

Airflow Perf uses a return line, but it is manually controlled, used to shut off the engine, and to purge the hot fuel from the system for restarting a hot engine.

Some Electronic Fuel Injection systems may use a continuous return, as do some mechanical systems.

What kind of injection do you plan to use??
 
We had the fuel lines plumbed for a return but were told by an expert that it wasn't necessary. Been flying for 300 hours without it and have no problems what so ever.
 
Well that is the issue, I really haven't investigated the whole engine choices yet. So I guess I need to do some homework before completing this tank.

The other part of the story is that I was able to pick up a decent quality partially built wing kit and one tank is already built and without a return line.



Another question would be, if a return line is needed, can a retro fit be done on a completed tank?
 
Fuel Return

Except for the optional purge valve system, Lycoming engines do not require a fuel return line. Continental injected engines and some with carburetors such as the Bendix PS5 all require return lines.
 
Another question would be, if a return line is needed, can a retro fit be done on a completed tank?

Yes, not hard at all.

I had to do that on my 10. You just work through the fuel sender hole, before installing the sender.
 
Return line doesn't necessarily have to go to the tank itself. On my AFP system, a purge line tees back into flow line from right tank. When purging, I just make sure tank selector is set to the left tank so I am pulling cool fuel through the system instead of just recirculating hot fuel.
Erich
 
ECI fuel injection systems for Lycoming absolutely require return line plumbing, and it must be plumbed thru a duplex fuel valve to go back into the same tank you're feeding from. The large volume of excess return flow is utilized by the high pressure pump to help cool itself.
 
It is so easy to install it early in the construction process, I say Do It!
Later, if you upgrade to a system that needs it, the effort will be nil and you will be grateful you put in the small effort now.
You will need this if you use a modern automotive based fuel injection system, like EFII or SDS.
I did it, I love it.
 
No tank return for Airflow Performance

Airflow Performance fuel injection systems do not require a return to the tank. If a purge valve is used, the return is plumbed to one of the tank feed lines before the selector valve. If the system already has tank returns plumbed in then you can use that. We have models of fuel injection systems that do not require the purge valve; FM-150, FM100A, FM200A and FM300B.

Don
 
ECI fuel injection system is essentially a Contintental style system adapted for use on a Lycoming.

Yep, originally it was known as the Airmotive Engineering fuel injection system.

It is so similar to the Continental system that the same set of gauges/fittings/valves/hoses that you use to calibrate the fuel injection system on an old Beech Debonair's IO-470 works perfect for calibrating the ECI system on an IO-360 in an RV :D
 
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