1986 Mercruiser runs rough only under load

Hey every one im new to the site and ive been fighting this problem for over a year. My boat has a 1986 mercruiser 140 in it. THE PROBLEM: The boat will run fine in neutral, revs up with no hesitation but the second it has a load on it will die down and not reach full RPM's and takes some time to get up to speed (not full speed). And seems to only want to utilize half throtle when it wont run good and any thing more than that it just bogs. Then again the boat will run great some other times like when i put it away this winter but its back to the same stuff this year. In the past when stuck on the lake with it running like crap i would hit it with some carb cleaner and it would clear right up and run great again. I have rebuilt the carb and checked the fuel filters. PLEASE let me know any suggestions you have i love the boat when it runs but hate it when i doesn't

Re: 1986 Mercruiser runs rough only under load

Have you checked your timing lately? You could also have a distributor wire issue. Could be loose or weak.

My boat was doing something similar and it took me weeks to discover that I had a weak connection on the negative terminal of the coil. Just enough to give my boat about 3/4 power.

Re: 1986 Mercruiser runs rough only under load

I have not checked the timing but have been thinking that may be the problem. Im going to check it the next time i go out.

Thanks man