My carburated outboard motor is very hard to start when the boat has been sitting for a few days. It takes a lot of squeezing on bulb on the fuel line and cranking the engine to get it to start. After the first time, it starts and runs great. Could the gas be getting sucked out of the (3) carburators and fuel line back into the gas tank? Is there supposed to be check valve that prevents this? If so, where would it be? Any other explainations about why my outboard motor is so "cold blooded?"

The nature of older two strokes?

It could be a pinhole in the fuel line which would allow air to enter the line. This would let the gas flow back to the tank.

The check valve works the other direction, preventing gas from flowing if the line gets cut. They do stick sometimes though.

The most common cause of your problem is the pinhole in the line or an old, soft primer bulb. If you have not changed it in a couple years, start there. the bulb should pump up easily and remain firm even when the engine is running.

Well, I learned something new this weekend! The engine just would not start. I tried using some starting spray (either). I tried spritzing a little gas in the carburators. No improvement. Then engine just spit at me a little. Finally it started, but it only was running on 2 of 6 cylinders (the bottom one on each bank-I disconnected the spark plugs one at a time to see if there was any effect on how the engine ran). Eventually the engine warmed up and ran perfectly on all 6 cylinders. So, I am now thinking that my problem is spark, not fuel. Is there anything besides the stator that would be common to 2 cylinders on each bank? Any other ideas? I hate to take my boat in now and be without it over my week of vacation next week!

Just shooting from the hip here, but some engines had multiple coils. One dedicated to a couple of cylinders. Possible bad ground or maybe bad coils, IDK.....

Some models of outboards had a choke system where you had to push the ignition key in when starting cold or the choke would not activate. It's possible that there is a special procedure for starting since you say it ran fine once warmed up.