A fuel demand valve that opens with minimal engine suction pressure. The fuel demand valve has an inlet housing and an outlet housing with a valve door in the outlet housing that moves to allow flow through the valve when exposed to a pressure difference sufficient to overcome a spring internal to the outlet housing. The inlet housing includes a shelf, and two gaskets, one large and one small, are disposed between the shelf and the valve door such that they define different surface areas on the valve door. The different surface areas define the amount of force required to be exerted on the valve door for fuel to flow when exposed to fuel supply and engine suction pressures. The different surface areas provide a mechanical advantage whereby lower suction pressure from the engine exerts the same force as a higher fuel supply pressure on the valve door enabling lower fuel pressure operation.