When the suction gauge shows zero or a vacuum, how should priming be checked?

• A. Inspect for air leaks in suction line.
• B. Inspect for air leaks in suction line, ensure water source is available, and verify priming device is functioning.
• C. Increase discharge pressure.
• D. Shut the pump down and wait.

Answer: (B)

When the suction gauge shows zero or a vacuum, the pump isn’t held primed and water can’t enter the impeller. The repair focus should be on restoring a sealed suction and a functioning priming system. Start by looking for air leaks in the suction line—loose fittings, cracked hoses, or bad clamps can let air seep in and prevent a proper prime. Next, confirm a water source is actually available to feed the priming device or the suction line; a dry tank or an empty reservoir will break the priming cycle. Finally, verify the priming device itself is working as intended—check that the primer or ejector is operating, that any valves are in the correct positions, and that there are no blockages or failed components in the priming circuit. If any of these are faulty, water won’t be drawn into the pump and the gauge will stay at zero or show a persistent vacuum. Increasing discharge pressure won’t fix a prime issue and can cause cavitation or damage, and simply shutting down and waiting doesn’t address the missing prime. By addressing leaks, confirming water availability, and ensuring the priming mechanism functions, the pump can regain prime and draw water properly.