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Fuel return routing

R

ribrdb

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I'm trying to figure out how to run the fuel return lines for my efii system in my rv9. Does anyone have photos of how they routed these in the fuselage?
In particular I'd like to see where you drilled the holes to penetrate the side skins. I haven't got the wings yet, so I'm not sure how much spare room I have around where the other fuel line holes are.
 
ribrdb said:
I'm trying to figure out how to run the fuel return lines for my efii system in my rv9. Does anyone have photos of how they routed these in the fuselage?
In particular I'd like to see where you drilled the holes to penetrate the side skins. I haven't got the wings yet, so I'm not sure how much spare room I have around where the other fuel line holes are.
Click to expand...

For fuse routing, I just put mine along the front of the spar right next to the main fuel line coming in. As for getting it back to the wing, that depends on where you put return fitting on the cover plate. Here's a pic of my wing root where I have both lines coming through, you'll just need to measure carefully and figure out where to put the hole.

100_0090_zps93b25229.jpg
 
What fuel injection system are you going to use? Most don't require a return line. However, the Airflow Performance setup has an optional purge line that can be plumbed into your fueil line just after the valve.
 
Bill, he mentioned EFII, which requires a full-size return line to each wing because of the fuel-rail design. :)
 
You really don't want to have your return line tie into the feed line just upstream of the valve, because the electric motor spinning the pump uses fuel to cool it. The fuel picks up a little heat and if you are in a low-flow state (like on the ground, or prolonged descent) that warm fuel recirculates and continues to pick up more heat - until finally you can it warm enough that vapor bubbles form in the low-pressure side of the pump and you get vapor lock. By far the better design scenario would be to return it all the way to the tank to avoid heat-soaking that loop of fuel.
 
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