help with my boat please
I need help wih my boat please, you guys are MUCH more helpful than the boat forums.
I have a late 70's merccruiser 120 I/O (basicly a 4cyl chevy engine). When I am in the water under load I can not get over 2000rpms.
Tonight I started to pull the spark plugs while the engine was running to see when happened. When I pulled #1, nothing, ran the same, #2, began to die, #3, began to die also, #4 same as #1, nothing happened.
I checked the compression on all cyls. and #1 @ 70, #2 @ 130, #3 @ 130, #4 @60.
Last year I had trouble but while I was out the last time I advanced the timing while I was out and it took off and got up on a plane. (I got the boat at the end of the season with no stern drive and the boat was free).
What could be the problem and where should I look next? Could it be a valve stuck open (I hope not pistons)?
PLEASE HELP....its boating season.