Why do not the pumps of coal-fired boilers absorb water?

Question details (Performance):

Water pumps do not absorb water.

The hands of the pressure gauge and the vacuum gauge beat violently.

Answer: Fault reason:

The water injected into the pump is not enough.

Air leakage of water pump or instruments.

Troubleshooting:

Add water to the pump.

Tighten or block the air leakage.