120 Mercruiser hard start when hot.

Have a 86 stingray with a 120 mercruiser. 153 cid gm w merc carb. Got it a month ago and first few times out was great no starting issues but had hesitation at half throttle when hitting throttle to get on plane. would bog down and pick right back up and was good to go. Replaced all fuel filters checked plugs for fouling, rebuilt carb and looked for water in fuel. Last time out still had hesitation but now has a hard start when its warm. runs great for 20 min stop to fish and doesnt like to start back up. Ignition had been updated to electronic to remove points. cap and rotor are like new, no wear and no cracks. Tested voltage at coil today on a whim. Was only 6 volts and would drop to 2-3 volts when cranking. I am assuming that could be the next piece of the puzzle. Anyone else have any other ideas to try and get it all good?

The choke plate all the way open when warm ?

I have had issues with the choke plate also.

Tested voltage at coil today on a whim. Was only 6 volts and would drop to 2-3 volts when cranking.

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Did you leave the resistor wire in place when you changed the ignition? I thought the coil momentarily gets 12 volts from the starter when starting and then the resistor drops the voltage to 8-9 volts. Maybe I'm wrong...don't have a schematic diagram.

Here is an update. I replaced the coil and got it to fire. was better voltage but still would drop when cranking. I tested at the selonoid and got 3 volts coming from selonoid on cranking. Took it apart for a cleaning and it was quite coroded. Replaced the selonoid and fires up nice and easy now! She is still cold blooded though! Guess its just how some old boats are. Will do some more choke adjustments and fine tuning from here on out! Hope the selonoid trick helps out some others that were in my perdicament! Happy Boating to all!

Readjust the choke.Replace the fuel safty valve on the tank.I hear so many people having problems with their boats starting or stalling after they rebuild their carbs this year.Cleaning the insides of the carb is most the problems I found.People like to use gumout to clean their carbs.Or other types of carb cleaner.As you have as you stated a 1986.That's a old carb.Old carbs thru out time makes their own marks & grooves so to speak.Most carbs have a ball bearing seated at the bottom of the carb.Or near/under the accelerator pump spring.That seat & ball bearing is worn to match each other from time & use.When,people think of cleaning their carbs.They have no idea when they clean they are making that ball bearing a looser fit from cleaning.To make this a shorter expaining.Some people will know as if they ever bought a use carb from a junk yard.You you search for a good carb.People think to find the newest or cleanest carb.Wrong.That means that carb was most likely rebuilt before.You can only rebuild carbs so many times until they are done- junk.The dirtest carb is the best carb.Mean's never touched or opened.Like factory.