Mercruiser 50 MPI 260 HP Wonbt Stay Running HELP

"First outing this season and

"First outing this season and after 20 minute cruise to our favorite cove, we anchor for an hour or so and when we're ready to leave, engine starts but dies as soon as I place into gear. Fellow boater tows to launch and on the way, start the engine and stays running. Unhook tow line and boat performs perfectly back to the launch. Next outing and the engine starts and dies. Replace fuel filter, same problem. Noticed when I removed the fuel filter that it was nearly empty. Removed new fuel filter and filled with fuel and engine continued to run fine so long as I did not shut it off. As soon as I shut off the engine and re-start, engine dies. Remove and fill fuel filter & engine starts & runs fine until shut off and re-start then will not remain running when re-started. During winter storage, fuel tank was filled and added sta-bil marine fuel additive. Fuel did contain up to 10% ethanal. What is causing the engine to die if I don't fill the fuel filter before starting. HELP! Boat is a 2005 Sea Ray 200 Sundeck powered by a Mercruiser 5.0 liter MPI 260 HP."

Fuel seems to be draining back

Fuel seems to be draining back into the tank. Check the anti-drainback nipple on the fuel tank where the fuel line attaches. Can you hear the fuel pump run when you first turn the ket to the RUN position?

"When I turn the key to the on

"When I turn the key to the on/run position, you can hear the fuel pump run for a short time. I think I'll disconnect the fuel supply line to the fuel filter base and turn on the key to see if I get fuel. What should the fuel pressure be running and not running? I'll also check the anti-drainback valve as well. Thanks!!!"

"I'd also go over the fuel

"I'd also go over the fuel line - from the tank to the pump - and look for a cracked line or fitting or a loose clamp....any air leak will adversely impact fuel delivery, especially on an injected system. cheaper shutoff valves have been known to leak air, too."