The present invention relates to a diaphragm carburetor for an internal combustion engine. 
DE 22 55 594 discloses a diaphragm carburetor for an internal combustion engine, according to which an impulse pressure driven fuel pump is disposed in the carburetor housing.  The fuel pump is embodied as a diaphragm pump, the diaphragm of which separates a fuel conveying chamber or a pump chamber and an impulse chamber or an operating chamber.  The impulse chamber is connected to a source of pulsating pressure, and the diaphragm is acted upon by a spring that extends through the impulse chamber.  At partial vacuum impulses, the diaphragm moves against the force of the spring, which during a change to pressure impulses enhances the fuel conveyance in the pump chamber and reinforces the fuel conveying pressure of the diaphragm pump.  With this known diaphragm carburetor, it is not possible to have a disruption-free operation, especially in conjunction with an internal combustion engine having only weak positive pressure impulses. 
It is therefore an object of the present invention to provide a diaphragm carburetor of the aforementioned general type with which it is possible to have a disruption-free operation of the internal combustion engine even with predominantly negative pressure impulses of the engine.