I am new to the forum and I searched but didn't find what I was looking for. Well one of our brush trucks is out of service and a couple of us mechanically inclined guys are gonna try and fix it ourselves first. We have a Briggs and Stratton Vanguard 18hp OHV pump motor. Well we just checked it and found to have no oil in it and all the fuel in the oil pan. What could have caused this to happen?