It has been reported that Engine room bilge pump was unable to take suction from Fwd. (P) bilge well while it taking suction efficiently from Fwd.(S) & aft bilge wells. What could be the most probable cause?

1. There is leakage in the bilge suction pipeline somewhere between the bilge wells and bilge pump
2. The Fwd. (P) bilge well suction valve might be leaking
2. The Fwd. (P) bilge well suction filter cover gasket might be leaking
4. The pump needs to be overhauled