Sometimes doesn't start?

[Itskial]

Recently bought a 2004 sugar sand tango super sport. 240hp merc. The boat starts and runs great.... until i shut it off. After being shut off it will not start for around 10 minutes.
If i let it sit for those few minutes, it will start up immediately. It doesn't always do this. Some weekends it will act fine, others it needs that cool down period to start again.
When i turn the key it sounds like it's not getting a spark. All plugs are new, coils are good. It's not overheating
Any advice is appreciated

 

[Bilmon]

Got a good, strong battery? These injected motors are real fussy about voltage. Voltage gets below a certain point and motor may crank quite well but it won't have enough to support the ECM. My son's 240 Tango behaved exactly like this, he has a after market stereo system which was using a lot of power. I finally convinced him to make sure the batt was always fully charged and problem went away.