A customer brought in this Sea-Doo that had been split at the bond line.The owner had left the Watercraft sitting at his dock during a July weekend with a 1/2 tank of gas. He jumps on his Seadoo and hits the start button and boom. Previously he had the starter replaced and new fuel line’s installed locally.The fuel line was installed with zip tie’s in place of clamps and gas pressure had built up during the hot day and pushed a fuel vent line off that was connected to the gas tank filling the hull with fumes.Reason for the flash over? The same mechanic that installed the fuel line installed a new starter and the bolt’s to the starter where an incorrect length.The bolts held the starter in position but allowed the starter to wiggle or move around while engaged.The Watercraft ground was on the engine case so every time the starter was engaged it arched to the block. Oddly enough there where no burnt wires or signs of an explosion other than the deck was separated and the hood was blown off.