594593 17.5HP Carburetor for B&S 591731 796109 31A507 15HP 590400 796078 498811 794161 795477 594591 794572 699937 Lawnmower Engines

What It Is

This is an aftermarket carburetor designed to replace a wide range of OEM Briggs & Stratton units (including 591731, 796109, 796078, and others) on single-cylinder, 15–17.5 HP lawnmower engines like the 31A507. It supplies the correct fuel-air mix for engines used on ride-on mowers, tractors, and zero-turns.

Fitment & Compatibility

• Check your engine model number: This carb fits B&S engines with model numbers like 31A507, but also many 15–17.5 HP units using OEM part numbers 591731, 796109, 796078, 498811, 794161, 795477, 594591, 794572, 699937, and 590400. Look on the engine shroud (not the mower deck) for the model/type/spec code.
• Verify mounting pattern: Measure the distance between the two mounting studs (center-to-center) – it should be 3.25 inches. Also check the intake port diameter (approx. 1 inch) and fuel inlet size (5/16 inch).
• Brand and deck size irrelevant: This carb is engine-specific, not mower-brand specific. It fits many brands (John Deere, Craftsman, Husqvarna, Troy-Bilt) as long as the engine is a compatible B&S.
• Aftermarket note: It is not an OEM Briggs & Stratton part, so gasket thickness and float adjustment may vary slightly. Expect to reuse your original choke linkage or throttle spring.

Key Things to Know

• Installation difficulty: Moderate. You’ll need a socket set, screwdrivers, and possibly a carburetor cleaning spray. Expect 30–60 minutes if replacing a similar carb.
• Common gotcha: The metal fuel line inlet may be tight; gently bend or use a short rubber hose adapter. Also, the included gaskets may be thin – consider adding a smear of grease to prevent vacuum leaks.
• Quality check: At $25.99, it’s a budget part. Inspect for burrs on the mounting flange or loose screws on the bowl. If the engine runs lean or rich, adjust the idle mixture screw (usually 1.5 turns out as a baseline).
• No warranty on fitment: Return policies vary, so confirm your engine model number before ordering.

Should You Buy It

Buy this if you need a low-cost replacement for a clogged or damaged B&S carb on a 15–17.5 HP mower engine and are comfortable with basic engine work. It’s a solid value for the price, but skip it if you demand OEM precision or if your engine model isn’t on the compatibility list – a wrong fit will waste your time.