2 Pack 694394 Carburetor Primer Bulb Fits Briggs & Stratton 694394 4178 494408 5084 Lawn Mowers Parts (Red)

What It Is

This 2-pack of red primer bulbs (model 694394) is a direct replacement for the push-button bulb that primes fuel into the carburetor on many Briggs & Stratton lawn mower engines. It’s designed for walk-behind mowers, small tractors, and other small engines that use a primer bulb instead of an automatic choke.

Fitment & Compatibility

Before buying, verify your engine’s model number (stamped on the valve cover or blower housing) and cross-reference with OEM numbers: Briggs & Stratton 694394, 4178, 494408, and 5084. This bulb fits many Briggs & Stratton engines from the 1980s through current models, including Series 450, 500, 550, 600, 625, and 650. Measure the bulb diameter (roughly 1 inch) and the stem length (about 0.5 inches) to confirm it matches your existing bulb. It will not fit engines with a separate primer pump assembly or those using a choke plate.

Key Things to Know

• Quality: These are aftermarket parts, but red rubber construction is durable and resists fuel degradation. They feel slightly stiffer than OEM, but most users report no leaks.
• Installation: Easy—just pull the old bulb out of its grommet, push the new one in until it seats fully. No tools required, but ensure the grommet isn’t cracked or brittle.
• Common gotcha: If the bulb doesn’t snap back quickly or feels loose, the grommet (not included) may need replacement. Also, if the engine still won’t prime, check the fuel line and carburetor needle valve, not the bulb.
• Pack size: You get two bulbs, so you have a spare for future use or for a second mower.

Should You Buy It

If your Briggs & Stratton engine’s primer bulb is cracked, stiff, or not sealing (causing hard starts), this 2-pack is a cheap, effective fix. It’s ideal for DIYers with basic mechanical skills and older mowers that don’t justify a full carburetor rebuild. Skip it if you need a complete primer assembly or your engine uses a choke system.