Briggs & Stratton 694394 Primer Bulb

What It Is

The Briggs & Stratton 694394 Primer Bulb is a small rubber bulb that forces fuel into the carburetor of small engines, enabling easier cold starts. It’s used on lawn mowers, generators, pressure washers, and other equipment with Briggs & Stratton engines requiring a primer bulb.

Fitment & Compatibility

• Check your engine model: This bulb fits many Briggs & Stratton engines, especially those with a plastic carburetor and a primer bulb housing. Look for the engine model number (e.g., 10T502, 12H802) stamped on the blower housing or valve cover.
• OEM vs aftermarket: This is an OEM part (Briggs & Stratton branded), so it’s a direct match for original equipment. Aftermarket bulbs may vary in rubber hardness or stem length.
• Measure the bulb: The 694394 has a ~1/2" outer diameter and a short, straight stem. If your old bulb has a different stem shape (angled or longer), this won’t fit. Compare side-by-side before buying.
• Not for all mowers: Avoid if your engine uses a primer bulb integrated into the carburetor or a separate fuel pump system (e.g., some overhead valve engines).

Key Things to Know

• Quality: Genuine Briggs rubber resists cracking and fuel swelling better than most cheap aftermarket bulbs. Expect years of use in normal conditions.
• Installation difficulty: Easy – 5 minutes, no special tools. Remove the old bulb by pulling it out of the retainer clip, then press the new one in until it snaps into place. Wear gloves to avoid oil transfer.
• Common gotchas: Ensure the retainer clip isn’t corroded or broken – if it is, replace it too (part 694395). Also, check for debris in the primer hole; a clogged passage can make the new bulb fail to prime.
• Test before full reassembly: After installing, pump the bulb a few times to confirm it draws fuel and doesn’t collapse. If it sticks or stays flat, check the carburetor gasket or fuel line.

Should You Buy It

Buy this if your Briggs engine’s primer bulb is cracked, sticky, or won’t hold a prime. At ~$8.50, it’s a cheap, reliable fix for a common starting issue. Skip it if your engine doesn’t use a separate primer bulb or if the carburetor itself is damaged.