Future RV 9 Flyer
Active Member
I am about to close up the fuel tanks on my 9 but have questions about needing a return line if going with fuel injection.Is a return line needed with all fuel injection systems?thanks in advance !dh
Van's Air Force
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Fuel return line
- Thread starter Future RV 9 Flyer
- Start date
Not needed with all systems, but they are needed with some systems, like any modern Automotive based Electronic Fuel Injection system that uses a fuel return regulator to control fuel pressure to the electronic fuel injectors.
That was a mounth full
If you think you might go that route, you might want to install a bulkhead fitting in the tank, and put a cap on it so you can hook up to it later without taking the tank off the wing?
I have such a system on my RV-8.
Be mindful that changes to the original plans will take time and add expense + weight.
That was a mounth full If you think you might go that route, you might want to install a bulkhead fitting in the tank, and put a cap on it so you can hook up to it later without taking the tank off the wing?
I have such a system on my RV-8.
Be mindful that changes to the original plans will take time and add expense + weight.
Scott Hersha
Well Known Member
It's not required for all fuel injection systems, but is required on at least two popular ones. It's far easier to pro-seal a fitting in the tank now, with a capped off end, than removing the tank to do it later. The new RV14 tanks have that provision as standard equipment, even though many people won't need it. There is a hole in the inboard rib and a fitting that come as standard equipment in the kit. I would put it in if I were you....... (#6 AN fitting)
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Agreed with the two opinions above - some need it, some don't, and it will never again be as easy to put it in as it is right now.
I would suggest putting one in and capping it, you can always use it (or ignore it) later as you wish. Quite a few folks worry about foaming in the first bay where the fuel pickup is, from the fuel return line dumping in there. I put my return line AN fitting fairly high in the tank end plate, and routed an internal line through the first bay bulkhead so the return fuel dumps into the second bay, and gravity-flows along the bottom of the tank back to the fuel pickup, to minimize any chance of air bubbles or foaming making their way back to the fuel pickup.
I would suggest putting one in and capping it, you can always use it (or ignore it) later as you wish. Quite a few folks worry about foaming in the first bay where the fuel pickup is, from the fuel return line dumping in there. I put my return line AN fitting fairly high in the tank end plate, and routed an internal line through the first bay bulkhead so the return fuel dumps into the second bay, and gravity-flows along the bottom of the tank back to the fuel pickup, to minimize any chance of air bubbles or foaming making their way back to the fuel pickup.
rmartingt
Well Known Member
I've done the same thing with my return line provisions, intending to fit an EFII system later on. It dumps out at the bottom of the second bay, several inches away from the hole at the bottom rear. It's a piece of cake to add when you're building the tank, and a big pain to do it later. I'd go ahead and provision for it now.
MikeyDale
Well Known Member
I believe you will would need to install a "Duplex" fuel selector. It returns fuel back to the left tank when pulling from the left tank and same for the right tank. The valve is like a double valve. Here is a link showing a picture of the FS 20x20-3 duplex valve, http://www.andair.co.uk/system/index.html. Vans has one on the website. http://vansaircraft.com/cgi-bin/sto...9&browse=airframe&product=fuel-selector-valve. FS 20X7T is the single Andair valve and a FS 20x20-3 is the duplex. Both are listed on this page......The believe biggest obstacle when going this rout is the plumbing. Things can get mighty crowded under that fuel valve cover!
Mark33
Well Known Member
Yes, the duplex valve takes care of the routing the fuel back to where it needs to go. Be sure to get the 90 degree fittings for the valve....it really makes the plumbing easy.
JanRV6UK
Well Known Member
Simple question I could probably find if doing a search ....
Which FI system does not require a return line to the tank ... and what are the downside ?? I need to be thinking about a engine purchase ... 360 with a CS prop .. I have not fitted a return line fitting to the tanks .. Yes at this point in time I could pull the tank off the wings and install one .. but doing it in the section furthest away from the suction strainer will require a access hole cut in the rear. ... and I do not fancy all that extra piping in the cabin (RV6) ... Appreciate some thoughts on this ...
Which FI system does not require a return line to the tank ... and what are the downside ?? I need to be thinking about a engine purchase ... 360 with a CS prop .. I have not fitted a return line fitting to the tanks .. Yes at this point in time I could pull the tank off the wings and install one .. but doing it in the section furthest away from the suction strainer will require a access hole cut in the rear. ... and I do not fancy all that extra piping in the cabin (RV6) ... Appreciate some thoughts on this ...
Jerry Cochran
Well Known Member
Returns for AFP F.I.
The -6a I sold to Dale Walter with IO360 Superior had no return lines, while the -7a purchased from David Domeir with Barrow-built IO-360+Airflow Performance F.I. has return lines. I rebuilt the entire fuel system and got almost(!) all the plumbing inside of a Van's standard cover next to the 6 port Andair valve. A combination of alum and stainless flex hoses did the job.
The -6a I sold to Dale Walter with IO360 Superior had no return lines, while the -7a purchased from David Domeir with Barrow-built IO-360+Airflow Performance F.I. has return lines. I rebuilt the entire fuel system and got almost(!) all the plumbing inside of a Van's standard cover next to the 6 port Andair valve. A combination of alum and stainless flex hoses did the job.
The very common Precision Silverhawk or Bendix does not require a return.
I believe the ECI and EFII both require a return.
I think Airflow builds two models for that engine, one with and one without. I went with the Precision partially for that reason and so far am happy with that decision.
I believe the ECI and EFII both require a return.
I think Airflow builds two models for that engine, one with and one without. I went with the Precision partially for that reason and so far am happy with that decision.
Mark33
Well Known Member
The EFII system does require a return line, but there's not any diffiult plumbing required in relation to the fuel tank. The following is from the EFII web site along with a link to that page which shows pictures of the installation.
"Fuel return line installation.
Electronic fuel injection fuel systems include a full return fuel system which feeds 20 to 30 gallons per hour through the engine fuel rail at all times. The engine uses what it needs out of this supply and the unused fuel is returned to the selected fuel tank. Below, you can see the installation of the fuel return into the fuel tank. Note - it is not necessary to disturb the original tank access panel which supports the fuel feed line and fuel level sender. A new 2.5" cover panel supporting the -6 return fuel bulkhead fitting is fabricated and sealed to the tank with pro-seal."
http://flyefii.com/customer_projects/duggan_rv8a/duggan.htm
