594281 Primer Bulbs fits for Briggs & Stratton 300E 450E 500E 550E 08P502 09P6S 09P7 Series Primer Carburetor

What It Is

This is a replacement primer bulb for Briggs & Stratton engines, specifically designed for the 300E, 450E, 500E, 550E series and models like 08P502, 09P6S, and 09P7. It’s used to push fuel into the carburetor for easier cold starts on walk-behind mowers, pressure washers, and small utility engines.

Fitment & Compatibility

• Engine series: Fits Briggs & Stratton 300E, 450E, 500E, 550E, plus 08P502, 09P6S, 09P7 (check your engine’s model number on the valve cover or shroud).
• Carburetor type: Designed for primer-style carburetors with a push-bulb fuel primer—not for choke or auto-choke systems.
• Measurement: Bulb diameter is roughly 1/2 inch; stem length about 3/8 inch. Measure your old bulb to confirm.
• OEM vs aftermarket: This is an aftermarket part, not OEM Briggs & Stratton. It’s a direct fit for the above series, but may not match OEM quality exactly.
• What to check: Pull off your old bulb; if the stem is cracked, torn, or hard, this will replace it. Verify the carburetor has a primer port (not a choke lever).

Key Things to Know

• Installation is easy: Pull off the old bulb (may need gentle prying) and push the new one onto the carburetor stem. No tools required.
• Common gotcha: If the carburetor is clogged or the primer stem is damaged, a new bulb alone won’t fix starting issues—clean the carb first.
• Quality note: Some users report the rubber feels slightly thinner than OEM, but it holds up fine for seasonal use. Expect 1-2 years of life in normal conditions.
• Price vs value: At $7.99, it’s a cheap fix. A dealer OEM bulb can cost $10-15, so this saves a few bucks if you’re on a budget.

Should You Buy It

Buy this if your Briggs & Stratton 300E-550E series mower has a hard, cracked, or missing primer bulb and you want a quick, low-cost fix. It’s a solid aftermarket option for DIY repairs, but skip it if your carburetor is gummed up or the primer port is damaged—you’ll need a full carb service first.