On a siphon hose in a kettle, what causes the check valve to jam open?

On a siphon hose in a kettle, what causes the check valve to jam open?

• A. Excess carbon buildup around the pump
• B. Low fuel level
• C. Damaged hose
• D. Overheating

Answer: (A)

The key idea is that a check valve must seat tightly to stop backflow. Excess carbon buildup around the pump creates a sticky, abrasive film and roughness that prevents the valve disc or ball from seating fully against its seat. With the seating compromised, the valve remains open or cannot close properly, so fuel keeps flowing backward and the valve appears to be jammed in the open position. This deposit-driven sticking is a common cause because it directly interferes with the moving parts and seating surface, unlike a low fuel level (which mainly affects priming), a damaged hose (which usually leaks or loses pressure), or overheating (which could warp parts but doesn’t specifically cause the valve to stay open due to carbon deposits). Regular cleaning and avoiding buildup help the valve seal reliably.

The key idea is that a check valve must seat tightly to stop backflow. Excess carbon buildup around the pump creates a sticky, abrasive film and roughness that prevents the valve disc or ball from seating fully against its seat. With the seating compromised, the valve remains open or cannot close properly, so fuel keeps flowing backward and the valve appears to be jammed in the open position. This deposit-driven sticking is a common cause because it directly interferes with the moving parts and seating surface, unlike a low fuel level (which mainly affects priming), a damaged hose (which usually leaks or loses pressure), or overheating (which could warp parts but doesn’t specifically cause the valve to stay open due to carbon deposits). Regular cleaning and avoiding buildup help the valve seal reliably.