appreciate someones help. 89 20hp merc int. runs on one Cyl

[deejathome]

1989ish 20 hp merc. It starts when I launch it, but it only runs on the top cylinder. Very slow. If I take the top cylinder plug wire off, it wont start on the bottom cylinder. <br />If I run it on one cyl for 10 minutes or so, the other cylinder seems to pop once or twice for a second, then all of a sudden it jumps up to full speed on both cylinders. Then it runs fine. Every start after that is fine. Even the next day at the lake it runs fine. But if it stands for a week or so on the trailer and I launch it again, the same thing happens. I changed both plugs and wires. The carb has been rebuilt and cleaned. <br />Will my 12V elec tester work to determine if power is running through the coils?<br />I would appreciate any help anyone could give me as to the root of this problem. Thanks alot from Winnipeg Canada.

 

[SHUMAKEB]

Re: appreciate someones help. 89 20hp merc int. runs on one Cyl

You might want to check the compression of each cylinder.