F115 intermitten fuel problem

I checked the fuel pump with a meter for 12 volts with the key on. It functions like it should, jumps to 12 then back down to zero. If the boat starts and runs it stays constant at 12.7-12.8.

The problem is sometimes the pump doesn't run. Is it possible for the pump to be defective and run sometimes and not other times?

[99yam40]

Yes it is possible for it to get voltage but not turn,any electrical motor can do it if they stick or bind up . I have read were a tap sometimes will get them moving again, but I would not trust one I had to tap to get going.
you just need to see if it is getting voltage when it is not running when it is suppose to.
Is the 12.7 psi the pressure it is suppose to have?