EJ conversion fuel system - www.OffroadingSubarus.com

Fuel System for EJ22 converted EA81's

Written by Thomas Paine - Phizinza

Just as a note, there are quite a few different types of original setups for the carbed EA81. These changed through the evolution the EA81 had from 80 to 94. Your system may not have a return line.

The original fuel system in my Brat had 3 lines coming from the engine bay through the cabin door trim and into the back. These lines consist of a 3.2mm return fuel line, a 6.3mm tank vent line and a 8mm fuel feed lline. The ventilation system contains a vent box which sits in the right rear fender. This box has two 6.3mm vent lines form the tank and the vent line from the engines charcol canister. The idea of the two vent lines from the tank is to have a vapour and drain back setup. So one of the lines from the tank to the vent box will go into the bottom. The other wil go in the top. Then theres the line which goes into the vent box from the engine bay.
I still wanted to keep the vent system on my Brat as I believe that it is better for hte enviorment and for fuel consumption. The vent tank in the fender looks like this on the inside if you are interested.
...........................tank vent......................
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.....canister vent - fuel drain back vent..

I used the "tank vent" pipe that goes from the tank to the vent box in the fender as a extra return line into the tank as I believe the 3.2mm original return line would not be enough. This still allows the tank to vent and drain back through the other vent and vent to the charcol canister. I also used the original return line, which you may not have in your EA81, I'm not sure which vintage they intreduced the return. But that's ok as I now think the 6.3mm return is big enough.

You will also need to run a new return line from the engine as the original of cause is only 3.2mm, if you even have it. Pull the door trim up and lay down a rubber fuel pipe, I chose the 8mm EFI hose as I didn't want it busting in the cabin or in the engine bay. I then used a T adapter to convert it down to the 3.2mm and 6.3mm you see in the pictures above.

The fuel feed to the pump and to the engine bay is easy. You'll just need to replace all the hoses with EFI grade and install a EFI fuel filter, the old carb one will NOT work. You will need to replace your old pump with a new one. I used a MPFI pump from a NA 88 wagon. This used a half inch fitting on the inlet side and the normal 5/8th / 8mm fitting on the pressure outlet. So I adapted the half inch down to the original fuel feed size.

I have been told you need a new wire forthe fuel pump. I'm not quite sure why you can't use the old wires, but I just ran a new wire with the new return hose. I used the chassis near the pumps bracket mount as a earth for the pump and then used the the extra wire from the EJ's fuel pump relay. This is perfect as it lets the ECU do it's warm up and pressurise fuel lines so it is easy to start. The EJ22 pressure regulator on the fuel rails do not allow much fuel to pass until there is vacuum, so if you wire the EFI pump to the old fuel relay and igntion then you run a big risk of burning out your pump or building too much pressure and blowing a hose. Also remember to solder all connections that aren't plugs.