After putting the engine back together for the piston replacement I'm getting a few codes including some misfire codes. It runs pretty good but I don't want to go over 3,000 rpm until it's broken in more. Before further testing, I want to remove the old gas in the tank which is a few years old. I got most of it out with a hose but the gauge is still on one full bar. How can I manually activate the fuel pump to drain the rest of the gas?