1989 evinrude 150 start in water issue

[Wesjdm91]

I have a 1989 evinrude 150 2 stroke that starts easily with the water muffs on but once it's dropped into the water at the lake it will not start unless brought out of the water. I've already rebuilt the carbs and cleaned out the jets and fuel passages. Any ideas? Thank you

 

[racerone]

Start with posting compression values.-----Does spark jump a gap of 3/8" on all leads ?-----You are pushing key in and HOLDING IT IN while cranking ?----Also take apart / inspect starter motor.-----Have battery load tested.

 

[faztbullet]

Weak battery,starter or high resistance in connections. The backpressure is lowering the cranking RPM so it wont generate suffecient ingnition voltage.

 

[Nick0151]

I’m not sure if any help but this could be a possibility

https://youtu.be/gkew5J0yIXo

 

[racerone]

Saw the plugged exhaust on one of those 50 Mercs years agio.----Big shop replaced a bunch of electronic ($$$$ ) parts and no better.-----Owner called me and asked if I was still working on motors.-----Found exhaust was only 25% open.-----I often post this simple check on this site for those 50 Mercury 4 cylinder motors.