how neccesary is a return line for a electric fuel pump?

You need to run a return type regulator in a return system instead of the dead head style regulator, as well as a pump that's capable of supporting a return.

Since a return is essentially a controlled "leak", this causes a pressure drop. The pump needs to be able to feed the fuel system and take the hit from the pressure drop of the return.


With a pump that's capable of supporting a return type fuel system and the proper return type regulator, there won't be any pressure variation.

A return, while not necessary, is certainly nice to have as it makes the fuel pump's life much easier. It keeps the fuel pump from fighting dead head pressure and that will make the pump ultimately last longer.

Also, especially with vacuum secondary carburetors, a return system helps keep the fuel in the rear bowl from stagnating and turning to varnish if you don't use the secondaries often. A return also helps keep cool, fresh fuel at the carburetor. With today's alcohol infected gas, that's a big plus.

Just remember a return and dead head type fuel system are totally different and need to be set up accordingly in order to work properly.

Either will work fine as long as all of the right parts are used for each system.