Yamaha 250 warm start issue

My boat has twin 2006 Yamaha 250 4 stroke outboards. F250TUR, Serial number 6P3 U 1005956 J and LF250TUR serial number 6P2 U 1012367 J. Both have around 400 hours on them.

I have a very intermittent problem that only happens after the motors have been running for a while. If I shut them down, and re-start them right away, they jump to life and start immediately. Once in a while ( sometimes a very long while later or not all on some trips), if I drift around a while with the engines off, I get the following behavior. Hitting start, the motor struggles to turn over, (acting a little like the battery is low). Back off the key and immediately hit start again, the motor jumps to life. One motor has done this on and off for two seasons. Now the other has demonstrated the same behavior. It’s like there is a vapor lock or compression thing that is broken by just touching the starter. I have brand new 27 675CCA batteries on each. The motors run from separate fuel tanks. Any ideas?

Are you saying the starter motor is struggling or the engine itself?

check all connections between battery and starter. This includes the battery switch, if you have one. Check for good spark on all plugs. Meter test for a drop in voltz.

Thanks for the response. It's very hard to predict when the problem will occur, but I will definitely keep your suggestions in mind. Thanks,

ClassicAQ. I wanted to say thanks for the tip. You were right on. Two trips now without the problem. All my battery connections were clean and seeming tight enough, I only got about an eighth of a turn on all the connections. It didn't seem like it would be the solution, but it appears to be it. Thanks, again. Boomer

Good to hear. Your welcome.