Johnson 55hp Won't Start in Water

[hgelzer]

1971 Johnson 55hp Won't Start in Water. When I have the boat in the water the engine will not start. I am only able to start it out of the water with muffs on. Most of the time I have to start the engine in gear out of the water. How do I fix this problem?

 

[mikeyzx2]

Re: Johnson 55hp Won't Start in Water

welcome to iboats!<br /><br />Henry, first let's get an idea of where we stand.<br /><br />1)compression check--good being 100+, and close together <br /><br />2)spark check--thick and blue? needs to jump 7/16"gap and be snappy<br /><br />3)carb and fuel system check--when was last overhaul?<br /><br />an unhealthy engine will often run fine on the muffs, but nothing when in the water due to backpressure. <br /><br />could be weak spark, no spark on a cylinder, could be lower compression.

 

[R.Johnson]

Re: Johnson 55hp Won't Start in Water

You could have an exhaust cover gasket leaking water into the cylinders. Have you ever tried cranking the engine with the plugs out to check for water?