Fuel Primer Bulb 8 mm (Manual Rubber Pump)

This 8 mm fuel primer bulb is an indispensable accessory for any small boat engine. It allows you to manually prime the fuel – pumping it through the hose from the tank to the engine – which is especially useful for the first start of the day or after the fuel system has been disconnected. The end fittings are 8 mm, making it compatible with the fuel hoses commonly used on outboard motors.

The operating principle is simple: insert the bulb in-line on the fuel hose between the tank and engine (the arrow on the bulb’s body should point toward the engine). When you squeeze and release the bulb, the internal check valves create a one-way flow – fuel is drawn from the tank and pushed toward the engine, without draining back. After a few squeezes, fuel fills the carburetor or fuel filter, and the engine can start more easily.

The bulb’s black body is made of fuel-resistant rubber that won’t swell or deteriorate from exposure to gasoline or diesel. The material stays soft and pliable even in cold temperatures, so you can use the primer in cooler weather without it becoming too stiff. The design is compact and lightweight – you can leave it installed in-line permanently; it won’t get in the way or take up significant space. It weighs only about 70 grams, yet it’s sturdy enough for regular use.

This primer pump is universal – suitable for gasoline systems (e.g., boat outboard engines, motor dinghies, RIBs) and small diesel engines (generators, diesel heaters, etc.), as long as it’s used with the appropriate hose diameter. It’s particularly valuable when the boat has sat unused for a long time and fuel has drained back to the tank – a few pumps and the motor receives fuel without excessive cranking. Likewise, if the engine has stalled due to running out of fuel or after a filter change, this bulb helps quickly restore the fuel supply.

For optimal performance, ensure the connections on the bulb’s nipples are tight with hose clamps to avoid sucking in air. There’s no special maintenance needed – it can remain in the system full-time. This is a tried-and-true basic tool that greatly improves the starting reliability and operation of small marine engines.