On a return system the pump runs flat out whether the engine needs the fuel or not, and everything it does not use goes back to the tank warmer than it left. Slowing the pump down during idle and cruise is the fix, and the ReturnX does it off a manifold pressure signal rather than a switch.

Aeromotive 66164 ReturnX Return-Type Pulse Width Modulation Controller Kit Features:

• Stand-alone fuel pump speed control for return-style fuel systems.
• Configured for a single pump in supercharged applications.
• Supplied stand-alone MAP sensor reads manifold pressure past the supercharger or turbocharger.
• Primary and secondary outputs with a leader and follower strategy.
• No relays or Hobbs switches required.
• Works with carbureted and EFI setups.
• Reduces fuel heating, pump noise and pump wear at idle and cruise.
• A return or bypass type fuel pressure regulator is required.