Fuel Pressure & VolumeThe relationship between fuel pressure and volume is inversely proportional. As fuel system pressure rises, the pump's volume decreases. In addition, the force of a car moving forward (g-forces) and the friction the fuel encounters in the system thorough lines and fittings may also impede the delivery at the carburetor. In order to supply fuel in the most efficient way, you'll want to use adequately sized lines (typically 1/2-inch id) and fittings without sharp bends. As a rule, a 90-degree fitting is equal to adding several more feet of line into the system (about 10 extra feet of line). This means that it's better to use two 45-degree fittings to negotiate a turn instead of one 90-degree fitting. When routing your fuel line, be sure to keep the line away from exhaust components and moving suspension parts, and never route a fuel line through the interior of your car.
Remember that the fuel your engine needs has to be delivered past the fuel pressure regulator and the needles and seats, and the fuel delivery system competes against g-force and friction in the system. Also, make sure your fuel pump is mounted where gravity will help draw fuel to the inlet. Ideally this is at the rear, lower side of the tank. If this isn't possible, at bare minimum you'll have need to mount the pump near the tank, since electric fuel pumps are better pushers than pullers.
Measure At The Fuel Pump TerminalsSimply having power connected to an electric pump and being able to turn it on does not guarantee the pump receives the correct amount of voltage. Wire size, wire unions, and a proper ground are all equal and critical elements of a properly operating fuel pump. Most electric fuel pumps are designed to operate at 13.5-14.2 volts DC. To illustrate this, testing has shown that an A-1000 Aeromotive fuel pump at 80 psi will see a 40-percent increase in volume when voltage is raised from 12 volts to 13.5 volts. A good fuel pump electrical system will use a 10-gauge wire (sourced from the alternator charging stud) and routed to a 30- to 40-amp relay near the pump. Equally important is a good ground system wired to the frame and onto the engine block. A secondary ground-again, properly installed-to the underbody is also a good idea. To check your fuel pump's voltage, use a multimeter, and with the engine and pump running, measure the voltage output at the alternator. Next measure the voltage at the pump. If you find more than a .5-volt drop, inspect your wire size, connections, and ground system. If you do run across wiring issues, best to rewire the entire system.
Think of the voltage to an electric motor as fuel pressure to an injector; more pressure in equals greater volume out. Higher voltage at the fuel pump terminals increases motor torque, resulting in an increased rpm and flow volume for a given pressure. Again, you may have the best and most expensive fuel pump available on the market, but if it isn't properly wired and installed, it'll reduce your fuel system's performance.
Setting Fuel PressureYour system's fuel pressure should be generally set between 6 and 8 psi (measured at the carburetor) for a street engine (higher for a race engine). Keep in mind that fuel pressure is not fuel volume. Your pressure reading is only an indication of the level of restriction in the system.
Choose & Position The Right FiltersFuel filter type and placement are critical to achieving the proper fuel pressure and volume being delivered to the carburetor. A high-flow, fine-element fuel filter should be used between the fuel pump and carburetor on the pressure side, not between the tank and the pump on the suction side.