85 Merc 5.7 260 with hesitation

[tbird811]

The money pit is wearing me down. Started the boat at the beginning of the season and it has a hesitation when trying to take off...you basically have to feather the throttle to get away. I have changed the points, plugs, condenser, distributor, checked the timing, the dwell, conducted a compression test, had the carburetor rebuilt, but still no improvement. It seems to be fuel related. Once you get it wide open, it seems okay, although the RPMs stay below 3850. I am told it should go to 4300. Any suggestions?

 

[fishless]

I have the same problem same engine. Did what you did plus installed electronic ignition. Talked to a marine mechanic and auto mechanic and they told me that I might have weak valve springs, poor compression or a bad cam. My engine only has 700 hrs for 25yrs old. I did a compression check and found a few cylinders off by 20%. I'm starting off with the cheap route and getting the heads rebuilt, should know in a week if this works. If not then it looks like a total engine rebuild. ouch...

 

[guyjg]

tbird811:

What were the compression readings? What prop is on it? The floatation foam could be waterlogged adding weight. Is the floor (wood) wet under the carpet? That's a telltale sign of water logging. Does it still hesitate? Could be a worn timing chain.