Originally Posted by m3chhawk

You should be good...

For reference: That pump will pull 10-15 Amps depending on load. We are probably closer to the 10A level.

The new wire (12AWG) for 10 feet at 15A, voltage will drop ~ 0.5 volts
That factory wire (~18 AWG) at 10 feet (who knows how long it really is) at 15A, voltage will drop ~2.0 volts. 18AWG at 15A will drop 0.2 volts per foot.

The voltage drop issue was hit or miss anyway, so the fact that you are improving it at least 1.5V at full load, that extra 0.2V won’t make a difference in this case.