Patent ID: 8240292

Claim:
A fuel system for supplying fuel from a fuel tank to a carburetor for an engine having an intake manifold, comprising: a fuel filler cap for the fuel tank having a body removably engaged sealably to the tank, a pressure relief valve integrated into the body for relieving superatmospheric pressure from the tank, and a vacuum vent valve integrated into the body for relieving subatmospheric pressure from the tank; the fuel tank having a vapor dome and liquid fuel is gravity fed from the fuel tank to the carburetor; a biased closed pneumatic fuel shut-off valve orientated between the fuel tank and the carburetor, the shut-off valve having a housing, an inlet chamber defined by the housing and a cooperating inlet diaphragm, an outlet chamber defined by the housing and a cooperating outlet diaphragm, a dynamic chamber being defined axially between the cooperating inlet and outlet diaphragms and communicating with the intake manifold, a flexible third diaphragm disposed operatively in the dynamic chamber and being responsive to a vacuum pressure from the intake manifold, and a valve head engaged to the third diaphragm; and a conduit communicating between the inlet and outlet chambers which are exposed continuously to internal pressure of the fuel tank.