I'm no expert but I have been reading a lot on this forum and own an 03 Outback LS. However, assuming that your starter will work and the boat will attempt to start then I would check the fuel system all the way through. Maybe try to blow some air through the fuel line and see if it's clogged. I would also probably check the inline fuel filter and see if it is clogged. Maybe not good advice but make sure the boat has gas and if it's old you could pump it out and try new gas.