Took jet ski out had old fuel started off good then lost power an started blowing white smoke

how old is gas in tank #2? sounds like lousy oily gas. white white smoke or blueish? white white sounds like heavy moisture. blue is oil

water in the fuel, you buy some stuff to resolve fuel issues i think call fuel restore. the stuff red or off pink color add to the fuel.
once do that i would drain fuel tank or
run high octane booster, you need to remove all water from the bike or you will have problems bike, cylinder, head, fail plug, running poorly until you remove all forms of water in the engine area and fuel areas. it depends on what you place the bike value or fun/toy
or professional rider

Any motor that runs and then develops sudden stopping symptoms gives me suspicions of fuel delivery problems.
I'm not familiar with your machine, but I would be looking at the fuel filter as probably plugged up.
Wild guess, but sometimes I luck out.
Cheerfuls.

what colour smoke , correct fuel ??

are all cylinders working ? carbs might need cleaning ! what compressions have you ? 100psi min !!

Yes, coolant is the most likely cause of white smoke.. Head gaskets are in order

A malfunctioning carburetor (running too rich) , will blow white smoke. I would start by checking the choke plunger, the seal could be leaking fuel. The plastic cap that holds the plunger on could be cracked and not holding the plunger in all the way. If you have re jetted the carburetor, perhaps the jet is too big. Your air filter could be plugged with dirt. All these things could cause a rich condition that would cause white smoke.

If the teeter/totter needles are gummy or covered with moisture corrosion it could be the reason the machine is so hard to start. When storing the jet ski's syphon all the gas out and burn it in your car or truck. Even if you stabilize it it wont be good fuel in the spring. Your plastic tank will not rust so remove the fuel. You may be able to clean them up by running a tank of Chevron Techron through them. Before riding we charge are batteries and start are jet ski's on the trailer/lift before dropping in the lake. This saves the battery. It takes more juice to start the boat in the water.