Changing Oil On Inboard My Bayliner 1988 5.0 Inboard/outboard Engine Wont Run - It'll Turn Over All Day But Never Start.?

My bayliner 1988 5.0 inboard/outboard engine wont run - it'll turn over all day but never start.? - changing oil on inboard

I ran last year. This year I changed the spark plugs, oil, oil filter, fuel filter and checked all fuses. when he changed the fuel filter, he forgot about the new filter before installing fill of gas, but after trying to start my boat i rarely check the fuel filter and fuel is now full. Help?