Mercruiser Ford 302 I/O 1976 quits when warm

[granitecanyon]

Bought a 1976 Steury houseboat...a fixer-upper. It has a Ford 302 I/O 188 hp Mercruiser engine. Runs great except now it will just quit when motoring along at trolling speeds, usually when warmed up.

Not being a mechanic I turn here for advice. My 23 year old son (and his friend who's Dad is a mechanic so he knows a little) were stranded yesterday on a big lake here in Michigan on the second day of their 2 day adventure. He claims there was no spark either at the plugs or even at the distributer. After being towed and then trailered home we (my neighbor who knows a little about motors) checked and got spark at the plugs and distributer and, in fact, it started for us in the yard.

My son said it just quit several times during the 2 days but always started back up again.

So, any advice? Do I start with new points? Can the coil get hot and then not work? Should I put a new one on?

Not to complicate the issue but someone else told me there is a switch where the shift cable comes in to the motor (a V-shaped bracket) that doesn't allow you to shift while under load and that it could go bad. We found that switch (I think). It moves one way in forward, another in reverse, and is in the middle in neutral. Not really sure how that all works but it would seem that is NOT it if it just quits while running under power at slow speeds.

Was hoping to go on an overnighter tonight with my wife if we can get if fixed today (Saturday). Any advice would be certainly welcome and appreciated!

Thanks from Michigan,
Ron

[jerryjerry05]

Start it and let it warm up.Then check the coil.Touch it and see how hot it is.
You should be able to touch it and not burn yourself.Too hot and it's bad.
If that checks ok then change the condenser.J

[frank246]

Turn on the ignition and measure the voltage between the coil + terminal and engine block (neg), it should read ~10volts !
When you measure 12v or 14v when the engine runs the resistor wire or in-line resistor is not working (or even missing), then the coil will overheat.
Good luck!

[Slicktified]

Just had a similar thing happening on my boat, would run about an hour, to an hour and a half, then quit. I repaced the coil and its been good to go ever since.

[Bt Doctur]

dont forget a bad condenser or a bad tach