The return-style fuel system is one of the most used in high-performance applications due to how it functions and the fuel pressure it provides. To get the most out of one of these systems you must ensure it is plumbed correctly and avoid introducing air into the system. Fuelab breaks down how to best plumb a return-style system and why it’s important in this great video.
A return-style fuel system can use either an electronic or mechanical fuel pump to send your fuel from the tank to a regulator to your carburetor or fuel injection system. Any excess fuel that comes through the system and isn’t used is returned to your tank via the fuel pressure regulator. In this system, the fuel pump runs constantly to provide the fuel. Since the fuel is kept consistently cooler it makes tuning an engine easier and the pressure more consistent, as well.
To make use of all the advantages a return-style fuel system can offer it’s important to make sure the plumbing is done correctly. Part of the plumbing process is where the return is placed inside your fuel tank. If the return is delivering fuel above the surface of the fuel level in the tank it will cause foaming and air bubbles to be introduced into your fuel. The video from Fuelab illustrates exactly why this can be a problem since it will cause spikes in fuel pressure and also cause the pump to run harder.
Check out the full video from Fuelab to get a better understanding of how a return-style fuel system works and what to do to ensure it is plumbed correctly.