Suction hose system is defective

• Suction hose end is not into water.
• Suction hose connections are not tight.
• Suction hose packings are defective.
• Suction hose is cracked or damaged.
• Vacuum or pressure gauge hose is cracked.

Cocks are not closed

• Pump drain cock is open.
• Muffler drain cock is open.

Hose connections are loose

• Vacuum hose.
• Vacuum gauge hose.

Vacuum pump is not working

• Strainer is clogged with dust.
• V-belt is damaged.
• Lever does not move.
• Rotor or shaft is seized.
• Vane(s) is broken.

Check valves, water stop valve are not working

• They are clogged with dirt.
• Diaphragm is cracked.

Mechanical seal

• Dirt is attached to it.
• it is worn out.

Throttle dial

• it is not set at START/SUCTION position.

• Suction head is too high.
• Suction strainer is clogged with dust, or plastic sheet, etc.

• Suction hose end is near the water surface.
• Suction hose is not held level.