93 xp runs on trailer but won't start when in the water

[cruisertom]

93 xp compression 135 rebuilt carbs, replaced fuel lines, new primer system, new battery, starter, plugs, plug wires ends etc. Starts right up in the garage idles well, get it to the lake, slide it off the trailer and won't start, cranks a sputters ocassionally but won't fire, removed seat and some smoke or exhaust came out. Took it back home and fired right off. What is the problem! Could it have to do with the waterbox?

[153stars]

Usally won't start in water means low battery. I have a " craftsman so called smart charger" that doesn't put a nice deep charge in small batteries. Smoke or exuast coming out sound like leak some where. Did you try running it on hose , maybe injesting water through some leak some where like exhaust gasket.

[KYHI]

You said it idles well in the garage - about 3000 rpm out of water is the normal idle - this will translate to about 1500 rpm while in water