Fuel Return for Injected Engines?

[aeroaddict]

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?

[Mike S]

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??

[sirlegin]

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.

[aeroaddict]

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?

[jrs14855]

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.

[Mike S]

Originally Posted by aeroaddict

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.

[aeroaddict]

Well, that settles it; Lycoming it is!

[erich weaver]

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

[Neal@F14]

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.

[SHIPCHIEF]

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.