I have a 1985 Mercury (SN 6419285) 4 cylinder outboard. It will only start when in neutral and full or wide open throttle, and not every time then. It has new plugs in it now. I just bought new plug wires but they won't be here for a couple days (two were really worn out). I used new car wires to trouble shoot with so the wires themselves won't fix this. I am installing a new gas tank when I get home, the old one is very old. The fuel filter is clean and good. I am buying new gas for the new tank, with no ethanol, for my test tonight. When I removed the fuel line from the filter and squeezed ball it shot like crazy so that all is good and the fuel line to tank is basically new. I'm also going to try some seafoam in the cyclinder, via plug holes, later tonight. Carbs were gone through last year but I'm not counting them as good just yet. Any idea would be helpful and appreciated. thanks

Replacing the gas can (was very old metal can) and fuel lind from can to bulb and bulb to engine fixed it.