Sierra 18-8004EP-1 EPA Primer Bulb 5/16

A replacement primer bulb assembly for fuel systems running 5/16 in hose. The bulb is a consumable: ethanol-blended fuel hardens the rubber over a few seasons until it will not collapse properly, and a bulb that stays hard is a bulb that is no longer priming the carburetor or the vapor separator.

• Hose size: 5/16 in hose barbs on both ends. Match the barb to your existing fuel line, not to the bulb you think you had.
• EPA series assembly, which is what current fuel system requirements call for on a replacement.
• Sold as a complete assembly with barbs, so it splices straight into the line.

Check the flow arrow before you clamp it down. A primer bulb installed backwards will feel like it is working and will not actually prime, and it is a genuinely common mistake because the bulb still squeezes either way. Use fuel-rated clamps, and replace the hose ends if they are stiff.