Is there any HP gain from using an electric fuel pump over a mechanical fuel pump? Since the cam is used to push on the rod that activates the mechanical pump, does that help the motor in anyway by not having to do that?

 

You won't notice any.

 

Not really. A mechanical pump doesn't use much power anyway. Also when swtiching to an electric pump, the power to operate it has to come form somewhere. Guess where, the engine, which turns the alternator.

I'm guessing that a FP only uses 60-100 watts, ~.1hp anyway.

 

You could try a lighter weight fuel pump pushrod if you want to recover some of that .1 HP.