MEMBRANE 91753M

Function and technical context

The 91753M diaphragm membrane is a critical component of the fuel supply circuit in small and medium displacement Mercury and Yamaha engines. This element acts as a differential pressure regulating valve, controlling the flow of fuel to the carburetor and maintaining the precharge pressure necessary for correct fuel atomization. It works in the feed line between the fuel pump and carburetor, ensuring that the engine receives fuel at constant pressure even during cruising maneuvers at varying angles. Its degradation causes fluctuations in the air-fuel mixture, resulting in misfires, loss of power and abnormal petrol consumption.

When to replace this part?

Diaphragm membranes progressively degrade due to aging of the elastomer and exposure to aggressive fuels, especially if the boat remains inactive for periods of time. Typical symptoms include difficult or impossible starting, jerking during acceleration, erratic running at low rpm, and loss of power in sustained driving. It is recommended to check and replace preventively every 2-3 seasons of intensive navigation or whenever carburetor maintenance is performed; This preventative replacement prevents unexpected being left in the water and costly emergency repairs.

Engine Compatibility

Equivalent manufacturer part numbers