Pump question

[Oregon Bob]

Does having a control valve in the pump output harm the pump when the valve is turned to restrict the water flow or even have it turned off?

 

[NeoTokyo]

It depends on what kind of pump you have but if you are putting more stress on pump then you could damage it if it is not intended to be regulated as so.
Some pumps use the water to cool themselves and restricting or stopping the flow could cause them to burn out.

Now I am applying general world knowledge (Like electric fuel pumps) that I have of most other non-prospecting related pumps but I would bet that they are very close in design.

If anything, call the company.