Why does the gasoline engine water pump lack suction?

[LaRyan]

Reasons for the gasoline engine water pump lacking suction: 1. Insufficient priming water: Before starting the pump, the pump (including the inlet pipe) should be filled with water. Otherwise, insufficient priming water or air inside the pump will prevent it from drawing water. The solution is to fill enough priming water and exhaust all air from the pump. 2. Inlet pipe leakage: Leakage mainly occurs at the connection between the inlet pipe and the pump body. Check if the rubber gasket is intact, tighten all connecting bolts, and seal the leakage point. 3. Filter head blockage: During installation and use, the filter head often gets clogged by mud, weeds, leaves, or other debris, preventing water flow. Remove the filter head for cleaning. To prevent re-clogging, cover the filter head with a metal mesh to block debris. 4. Shaft (oil) seal leakage: The shaft seal, made of oil-resistant rubber, may wear out over time, causing leakage. Replace the shaft (oil) seal to restore operation. 5. Low voltage: Low voltage reduces water output. Avoid using the pump during peak electricity hours and use larger cross-section wires. Excessive impeller clearance: The impeller clearance is affected by the conical ring. If the clearance is too large, adjust it or replace the conical ring. 6. Installation position too high: If the pump is installed too high, the filter head may be too shallow in the water, easily sucking in air and causing cavitation. It may also exceed the pump's specified lift capacity, resulting in insufficient water output.