Which bypass valve blocks fuel flow to the main jet to build pressure during cranking?

• A. Main
• B. Idle
• C. Auxiliary
• D. Pilot

Answer: (A)

Starting during cranking relies on a bypass path that changes how fuel is delivered, building pressure in the supply so the engine can start. The main bypass valve is designed to block fuel from reaching the main jet during cranking, which forces fuel through the bypass route and lets pressure rise quickly. That specific function is what makes it the correct choice. The idle, auxiliary, and pilot bypasses handle other operating conditions and don’t serve the same role of blocking the main jet to build pressure during cranking.