Skill: Engineering
Difficulty: 8
Uses Module: Yes
Can be done Remotely: Yes
Energy: None
Can be done more than once per Round: No (even if the pumping fails, it can only be attempted once per round)
Note: More than one point can be pumped. Each additional point increases the difficulty of the roll by 3.

Skill: Engineering
Difficulty: 8
Uses Module: No
Can be done Remotely: Yes
Energy: None
Can be done more than once per Round: Yes
Note: More than one point can be transferred. Each additional point increases the difficulty of the roll by 3.

Skill: Engineering
Difficulty: 11
Uses Module: No
Can be done Remotely: No
Energy: None
Can be done more than once per Round: Yes

Engines generate 1 point of energy per round at the start of the round automatically. Extra energy during phases with a round must be pumped out of the engine. Energy generated goes first to Helm, then to Guns, then Shields and repeats in that cycle (4 engines = 2 Helm, 1 Gun, 1 Shield).
Power generated by engine pumping can go wherever the player decides. It is not allocated like power is at the start of the turn (Helm then Guns then Shield). It does not have to all go to the same system. [YG 153] End of round power loss is one point per system (Helm, Guns, & Shield). Any system with zero does not lose additional power.
You can only pump each engine once/turn (it acquires a use marker). You can transfer power as often as you like, including from a used engine (without penalty).
There is no limit to the amount of power you can attempt to generate in a single action, except for the standard rule that you cannot attempt a roll you can't succeed.