My field box is made so the fuel bottle sits in the middle of it and has the lines to the pump ran in through a special cap I made and the pump is bolted to the side of the box. Then a coiled line goes to the plane.

It is 15% fuel, and runs fine, but after sitting for about a month and a half, my engine doesn't seem to turn the RPMs it used to and doesn't start quite as easily as it did last time I ran it.

Could it be:

A: The nitromethane evaporated out of solution, reducing the content to 0%

B: Water condensed inside the bottle.

C: The methanol evaporated a little, raising the oil percentage.

D: My junky old LA is trying to lay down on me.

E: Just my imagination.