Pump at Kickstart Pressurized

PROVIDING the pump is not rotating in reverse and running in its designed direction and a re-start is attempted, the start load (in-rush current & Torque) could be slightly less than if the pump is at a standstill

However, if the pump is rotating in reverse (as noted in the first answer) and you try to start the motor, you WILL snap something.

It might be the motor shaft, it might be the coupling, it might be the pump shaft. As the motor has to over come the energy in the pump from running backwards, the in-rush current (lets assume that you are not using a VSD and the motor is DOL) together with the torque produced could be far in excess of the BHP rating of the shafts or coupling as the motor tries to reach its running speed.

If there is a possibility of the pump/motor running backwards and your motor controller does not have a back spin detector, then you might want to look at fitting one & non-return valves in the flow lines.

That is one possibility

You don't say if the motor is started automatically or manually!

In either option if you continuously stop and start the motor, you are subjecting the motor windings to in-rush current, even if the motor is still rotating the correct rotation, and as I said maybe with reduced starting current, but starting current is still higher than running current.

The effect of the numerous starts heats the motor windings up to the point that they will fail. The motor requires a cooling down period between starts, this is always good practice.

If you are concerned about this, and I guess you are hence the post, then you might want to consider a restart timer in the motor control circuit to delay any restart giving the motor time to cool, I use 30 mins for my motors.

However, the motor you are using might be so oversized compared to the pump HP required that it might tolerate in the short term (some people might disagree) the starts and stops, but the strain on the motor windings, motor shaft, motor bearings & housing are still present and will have in the long term a detrimental effect on motor and pump.

So if possible avoid it!