'91 Yamaha I/O with 305 trouble starting when warm

[ryno1234]

As the title says, I have a '91 Yamaha stern drive with a GM 305. I pulled all that Yamaha YEMS system out and put in a standard electronic distributor.

Last year the boat ran fantastic - the best it has ever ran in the 10 years of owning it. This year, its behaving differently for some unknown reason. I can get the boat started when launching. It often dies and I have to start it again and keep the RPM's up for it to get warm. Once warm, the engine will idle without dying. This is nothing new and has always been a problem because the choke on the carb is broken. This has never been a significant issue as we've always been able to work around it.

Now, I'm experiencing a problem where once warm and shut down, the boat (sometimes) does not start and takes a period of multiple attempts at cranking before it will finally kick over over.

In the last 3 times out on the water, I couldn't get it started for 20 minutes 2 of the times and on this last time I couldn't get it started even after an hour and had to get towed in.

I've tried several things:

• Giving it more gas prior to starting
• Using starting fluid
• Making sure I use no fluid and no gas in the event that I'm somehow flooded in the first place.

It seems that giving it more gas or using starting fluid have not worked to my advantage. I'm surprised because I would think starting fluid might help start even a flooded engine (if that is even what's happening).

I just purchased a new carburetor just in case that is the issue which will arrive late this week, but I'd rather not keep throwing money at it.

Any ideas or troubleshooting techniques?

​​​​​​​Thank you!

 

[jesse_boston]

Could be your carb is leaking after you shut down, which can flood it. Pretty sure my merc is doing that too.
When the float gets old it can get saturated and not 'float' the way it is supposed to, so the bowl over fills

 

[ryno1234]

jesse_boston , thanks for the tip! I purchased a re manufactured carb which I would think would fix this issue. I assume they install new floats in these.

 

[Scott Danforth]

Depends on who rebuilt the carb