Engine trouble

[marty]

I have a 2000 mercruiser 250 hp 2 barrel inboard outboard. It starts and idles fine, I can rev it up in neutral with no problem. I can put it in gear and idle out the dock but as soon as I give it gas it stalls right away.I have changed the gas and water seperater in the fall. Is there anyone that has had this problem? Looking for some advice. Thank you.

clean the fuel tank filter and check the checkball if gas is being restricted in the tank

[Mxclutch]

I had the same exact issue last season. It ended up being the anti siphon valve on the fuel tank. So follow your fuel line to where it connects to the tank. Your fuel line will be connected to the valve. It will unscrew from the pickup tube. if you look inside you will see a small ball that has a spring behind it. You will probable see rust. You can clean it or replace the valve with a new one... If you clean it, make sure the ball moves freely when you push it from the tank side.
A new one is about 15 bucks.