Attwood Primer Bulb - 5/16" Inner Diameter Hose

The Attwood Primer Bulb with 5/16" inner diameter hose is an essential fuel system component for marine and small engine applications where reliable priming is critical to engine startup. Whether you're rebuilding a carburetor, servicing an outboard motor, or troubleshooting a fuel delivery system, this primer bulb restores positive pressure in the fuel line and ensures fuel reaches the carburetor or fuel injector before ignition. Mechanics and boaters depend on quality primer bulbs to eliminate vapor lock, prevent hard starts, and maintain consistent fuel flow in variable operating conditions.

The Attwood Primer Bulb features exclusive three-layer construction that sets it apart from single-wall alternatives—the inner, middle, and outer layers work together to prevent collapse under vacuum while resisting ballooning or bursting under pressure cycling. This engineered design maintains structural integrity through thousands of squeeze cycles and wide temperature swings, eliminating the leaks and failures common in inferior bulbs. The 5/16" inner diameter hose connection is the industry-standard size for carbureted outboards, personal watercraft, and small gasoline engines, ensuring drop-in compatibility with most fuel line assemblies without adapter fittings.

Technicians performing fuel system diagnostics or carburetor overhauls will appreciate the long-term leak-free performance that eliminates fuel seepage around the hose connection and bulb body. This bulb excels in both cold-start situations and warm-weather operation where fuel vaporization can create air pockets in the line. Replacement installations typically take minutes and require no special tools—simply disconnect the old bulb, slide on the new 5/16" hose connection, and secure with hose clamps. For anyone maintaining vintage or current small-displacement outboards, jet skis, or carbureted lawn and garden equipment, the Attwood Primer Bulb is a proven solution that restores reliable engine starting and eliminates troubleshooting guesswork.