Outboard that will not start in the water

[AuxTech2]

I have a 1995 200hp, had problems before starting, I cleaned and adjusted carbs according to the service manual. With the cups on in the yard the motor idles all day long, when I put it in the lake it idles for about 10sec then cuts off. After running the battery almost dead I took it back home in the yard and it idled with no issues. Is my motor allergic to the water?? Is this bad gas or electrical?? Thanks for the advice.....

[BQUICK]

Back pressure having exhaust under water can cause this if you have low compression. Do a compression test.....

Also, old fuel will be harder to ignite with the back pressure.