Motor cuts out

"I own a 2006 Bayliner 185 Bow

"I own a 2006 Bayliner 185 Bow Runner with a 3.0L mercruiser. Recently after running the motor for 20 to 25 minutes it stalls out and will not start unless it sits for about 15 minutes. When it finally does restart it will do it again after 20 to 25 minutes. During the period when it won’t start the motor just spins but will not fire.

I’ve ruled out a fuel problem as even spraying starting fluid directly into the carburetor will not get the motor to fire. I’ve also drained the tank and filled it with top grade fuel.

When it’s running it runs perfect. I think I have a spark issue. Is it possible that the ignition module heats up and cuts out? Then once cooled its ok? Or maybe a coil issue? Unfortunately it’s 2 months out of warranty and I’ve already brought to a shop and for $150.00 they told me there’s nothing wrong with it. I don’t want to start replacing things at random but it seems to me one of these things is the culprit. What do you think? Is there a way to test these components?

Thanks in advance for any help you can provide,

Steve"

"Or maybe a coil issue? That w

"Or maybe a coil issue? That would be my guess. Often a weak coil will run fine until it reaches a certain elevated temp then fail. You might buy a can of "Cool-it" or similar at an old timey electronics store and about the time you expect it to fail, spray the coil with this stuff and see if it continues to fire. Or try another coil. Hope you get it going. JW in Dixie"

"Steve;
Easy to check. Run it

"Steve;
Easy to check. Run it until it quits, then pull a plug wire and hold it near a ground to check for spark. Use insulated pliers or you may be the one sparking.
If no spark, the coil is the first suspect.
Funny how strange things happen immediately after the warranty has run out?
Rud"

"Steve;
Another prime suspect

"Steve;
Another prime suspect is the shift interrupt switch. When it quits, check to see if the switch button is centered in the V notch. Don't move the shifter into neutral before you do this check.
Rod"