Solar panel to charge 9 volts batteries, but need to power 120 volts pump
There are small inverters that plug into an auto cigarette lighter outlet. They look like an oversized USB adapter. One of those will provide 120 volts AC from 12 volts DC. It will not be very efficient and the motor may overheat due to the poor waveform, but it will probably be ok for a short time. You will probably need 8 C or D cells.

At 4 watts, the motor must be something like a small aquarium filter pump motor. The motor is very inefficient, so the stalled current won't be much higher than the normal running current.