I'm missing the model & year of the motor in question here, but perhaps the
symptom's generic enough that it won't matter:

Out on a friend's boat this weekend. He's got a 70 hp Evinrude 2 stroke, 3
cylinder. The motor ran nicely all day long, started easily at various
points. At the end of the day, while waiting for our turn at the launch, the
motor died at idle and refused to start again. Although there was plenty of
gas, we hooked up the 2nd gas tank just for the hell of it, with no results.
This guy beats the snot out of the boat and thinks it's funny, so I suspect
the boat's spirit is getting revenge. I mean, how many times can you
intentionally hit 3 foot wakes at right angles? But, there's probably more
to it.

If this were my boat, I'd drop it off at my dealer's, since I'm not well
versed in engines. If I screw up my lawnmower...oh well. If I screw up my
boat's motor on a day like yesterday, it could mean being stuck on Lake
Ontario on a day which began overcast, calm and hot, and ended up looking
like the perfect storm. But, my friend's nutty enough to work on his own
motor, so...

Anyone want to reorder or add to this checklist?

1) Expensive ignition module - bad? Without knowing the year of the motor
(yet), can't say for sure how it compares to my 1996 Johnson, which *does*
have an outrageously expensive module.

2) No spark for OTHER reasons?

3) Sudden failure of SOMETHING in the fuel system?

I'll be invited out on this boat again, so I'd rather see something SOLID
fixed, rather than hear "Weird....it's workin' fine now...hasn't happened
since".