How To Design A Fuel System

If you are using a factory gas tank, the return line should be as far away from the pickup as possible to prevent the returning fuel from frothing and disturbing suction. All that fuel going to the pump has to be replaced with air in the tank, so it needs a suitably sized vent with some kind of filter attached or fuel will stop flowing.

This is a BG King Enduro that is designed for a 2,000hp dead-head systemthat will see a lot of street time. It uses a heat sink (shown at right) to coolthe fuel and an internal bypass to eliminate the problems created by astandard dead-head pump and regulator. There is also a new Speed Endurothat feeds up to 500 hp for regular guys like us.

Holley also has an internally regulated pump for street use. The HP 125is a gerotor-style pump, so it's quiet, and it can feed up to 650 hp.

WiringThis is easy. You'll need to run a minimum 12-gauge or preferably 10-gauge wire from a battery source to the fuel pump using a relay, and then switch the relay on and off using a 12-volt source from the ignition key or, in some cases, a toggle switch. Since fuel pumps are simply electric motors, the amount of current supplied can affect the speed, and therefore the efficiency, of the pump. Ever had a low battery or a bad connection and had your starter spin really slowly, barely turning over the engine? Same thing. The minimum voltage you should deliver to the pump is 13.2 volts, but companies like Mallory advertise the maximum pump gph rating at 14 volts, so the closer you can get to the ideal between 13.5 and 14.2 volts, the better.

Just as the power wire is important, the ground wire needs to also be 12 gauge or larger and attached to a clean portion of the frame near the pump. If the pump is straining or getting hot, check the ground circuit first.