1987 Evinrude 70PH runs fine in driveway but not in water

[paulurban]

Engine will run in driveway with water connected to water intake. Idle OK, throttle advance OK. When placed in water (on trailer ramp), engine would not idle properly and when advancing throttle engine stalled. Never got boat off trailer.

Returned to driveway, engine runs fine again!!!!! Checked fuel primer bulb, seems OK, not soft. Full onboard tank of gas.

Anyone have an idea what is happening?

 

[hidef]

Re: 1987 Evinrude 70PH runs fine in driveway but not in water

Check your compression.

 

[paulurban]

Re: 1987 Evinrude 70PH runs fine in driveway but not in water

OK - the compression is 60 psi on all three cylinders.

What is the correct procedure to test compression?