753-08319 (3/Pack) 3 Line Primer Bulb for MTD/Craftsman/Troy-Bilt 316731932 316731933 316731934 316740930 316740970 TB685EC TB6044XP TB635EC TB685EC fits Yard-Machine Engines with Fuel line

What It Is

This is a 3-pack of replacement primer bulbs (part number 753-08319) for MTD, Craftsman, Troy-Bilt, and Yard-Man engines—specifically models with a 3-line fuel system. It’s the rubber button you press to push fuel into the carburetor for easier cold starts.

Fitment & Compatibility

Before buying, verify your engine’s model number (e.g., 316731932, TB685EC). This bulb fits MTD/Troy-Bilt/Craftsman/Yard-Man engines with a 3-line primer system—not 2-line or single-line. Check the bulb diameter: it should be ~1 inch across. OEM equivalent replaces part numbers 316731932, 316731933, 316731934, 316740930, 316740970. Works on TB685EC, TB6044XP, TB635EC, and similar. Does not fit Briggs & Stratton, Honda, or Kohler engines unless they share the same 3-line MTD-style primer.

Key Things to Know

• Quality: Aftermarket, but reviews indicate it’s durable and seals well. Some users report minor fitment variance compared to OEM, but it works.
• Installation: Easy—pop off old bulb, push in new one. No tools needed, but ensure the fuel line is seated correctly to avoid leaks.
• Gotcha: The 3-pack is handy, but you only need one at a time. Keep spares for future failures (common every 1-2 seasons).
• Check fuel lines: If the bulb fails, also inspect the fuel lines for cracks—old lines can cause air leaks and primer issues.

Should You Buy It

If you own an MTD, Craftsman, or Troy-Bilt push mower or trimmer with a 3-line primer system and need a quick, low-cost fix for hard starting, this 3-pack is a smart buy. It’s reliable, fits most common models, and saves you from buying a full carburetor. Skip it if your engine uses a different primer style (2-line or bulb-less).