That is correct - no return line. Cap off the existing return line. Don't use the horn as a power supply - splicing into an accessory circuit is dodgy and it will get constant power with the ignition off. Use a relay that takes power from the ignition circuit to trigger it (from the ignition side into the coil) and run power with a fuse straight off the battery through the relay so it is guaranteed a constant 12+v to run the pump. There is a throttle cable bracket that mounts to the rocker cover (most guys refer to it as a 'boomerang' - best way to describe the shape of it)