I could use some advice or direction to the below problem. My pontoon has a 2001 50 hp 2 stroke mercury on it. I used it on the 4th with no issues ran great. Jumped on it this morning to go for a cruise and it would just crank over like there was no fuel or spark. During the use on the 4th i did mix in sea foam to the 12 gallon tank. I used about 7 gallons of fuel that day. This is what ive done to it so far: 1. new fuel line and primer bulb 2. new spark plugs 3. installed a temp tank and fuel line The above didnt change a thing. I then cranked the motor over and threw it in gear quick. That would allow it to fire up but not to idle. After that I could put the lever in high idle and it would start but run terrible. I back it down to just above neutral idle and it would run but sputter. I then put it in neutral to idle and it would spit sputter and shut down after about 3 minutes.Unfortunately the boat is still in the water and the layout doesnt allow me great access to the motor (overhead only). My question is does anyone know something else I should check before pulling it out of the water? My thinking is the fuel filter under the cowl could be partially clogged or maybe the fuel pump is going out but im no outboard mechanic. I did install a temp tank with new fuel to rule out the fuel tank and lines after i was able to fire it up. It gave the same results as above though. Thanks for everyones assistance.