A good product that I've used with great success in getting fuel soak out of wood is a carpet stain remover called KR2. Its available from hardware stores like Ace. Spray it on the wood and let it sit and turn to a white power. Wipe it off, and go over the area several times with alcohol to make sure it's clean from any residue. I found the Monokote sticks as good if not better over the areas I cleaned with KR2 as it does fresh wood.

Hogflyer