Carburetor for Briggs & Stratton 31P977 331877 31P677, Fits Craftsman YTS3000 DLS3500 DYT4000 LT1000 17.5-20HP Lawn Tractor, Replaces 594601 591736, with Fuel Hose & Gasket

What It Is

This is an aftermarket carburetor for Briggs & Stratton 31-series engines (models 31P977, 331877, 31P677) commonly found on Craftsman lawn tractors like the YTS3000, DLS3500, DYT4000, and LT1000 with 17.5 to 20 HP. It replaces OEM part numbers 594601 and 591736, and includes a fuel hose and gasket for a basic swap.

Fitment & Compatibility

Before buying, verify your engine model number (stamped on the valve cover or blower housing)—it must be one of the 31P977, 331877, or 31P677 variants. The carb fits most Craftsman tractors with these engines, but not all LT1000 models; check your deck size (typically 42-54") isn’t a guarantee of engine match. Measure the mounting bolt spacing (center-to-center) and the fuel inlet diameter (usually 1/4" or 5/16") to ensure the included hose fits. This is an aftermarket part, not OEM Briggs & Stratton—dimensions and jetting may vary slightly from the original. If your tractor uses a different fuel line fitting or has a separate primer bulb, confirm compatibility.

Key Things to Know

• Quality variance: At this price point, expect a basic cast-metal carb. Some users report needing to adjust the idle mixture screw or clean out debris from manufacturing. Check the bowl gasket for a good seal before installing.
• Installation difficulty: Moderate—you’ll need basic tools (socket set, screwdrivers) and about 30-60 minutes. Remove the air filter housing, disconnect the fuel line, unbolt the old carb, and swap. The included gasket may need trimming for a perfect fit.
• Common gotchas: The mounting studs on the carb may be slightly longer or shorter than OEM—use your old studs if possible. The fuel hose provided is generic; you might need to cut it to length. Ensure the choke linkage is correctly aligned after installation.
• Performance: Expect similar performance to OEM for most mowing, but you may need to fine-tune the idle speed and mixture. If your engine ran rough before, replacing the carb often fixes surging and hard starting.

Should You Buy It

Buy this if you have a Craftsman tractor with a 31-series Briggs engine and need a budget fix for surging, poor idling, or fuel leaks. It’s a good value for DIY repair, but if you want exact OEM fitment or have a complex fuel system (e.g., electric solenoid), spend more on a genuine Briggs carb. For under $17, it’s a low-risk way to get your mower running again.