260 mercruiser stalling at trolling speed

[karma]

hope you can help me out with a place to start... last month 1 purchased a 28' bayliner with a mercruiser 260 I/O. The boat was not run for 2 years. Included with the boat was a folder with all paperwork, including repairs, tune ups, and winterizations. As best I can tell it was properly winterized after the last time it was run. When I brought it home, I put in 2 new batteries, hooked up the ears and it fired right up. I have used the boat 6 times or so trolling on lake michigan. The problem I have is that it appears to be loading up and will eventually cut out at its lowest speed (about 600 rpms). To remedy this temporarily, we drop it in neutral and rev it up a little bit when we feel it getting a bit doggy. At any other RPM there is absolutely no problem. Unfortunately I have to keep it at its lowest setting to get my speed right (2.4-2.6) for trolling. This is my first I/O. This week, I am going to try some Sea Foam in the carb and replace the plugs. Where should I go from there?? Thanks in advance for your replies.

 

[Don S]

Re: 260 mercruiser stalling at trolling speed

Your problem may be no more than needing a tuneup.<br />Any boat should be tuned up every spring, just sitting around does more harm than anything.<br />New plugs, (points and condenser if you have them) cap, rotor, plug wires if they are corroded or cracked. Then check the (Dwell if you have points) timing, advance timing and adjust the idle mixture. Also check that the choke is fully open.<br />Have you changed any fuel filters, engine oil and filter, drive servce? Don't expect it to work without maintenance...... that just makes things way more expensive than they need to be.

 

[Bondo]

Re: 260 mercruiser stalling at trolling speed

Ayuh,........ Given the history you have on this boat,........<br />Like Don says,.... Time is the Worst thing for a motor/drive...........<br />A Full,+ Complete Preventive Maintaince Service should be performed,... Even before the 1st launch,.. <br />Just to see Exactly what you bought.......<br />That's a Pretty Big Pond that you're playing on,....<br /><br />To get a handle on your trolling speeds,...... Try Either dragging a pair of Trolling Bags,.....<br />Or using Over-sized Trim Tabs,.Deployed Fully Down,......<br />Then you can bump up the idle speed,... My motor Loves to run 1000rpms,.. 18hrs. a Day,......<br />I can get down to 3/4mph/1mph at 650rpms,.......

 

[karma]

Re: 260 mercruiser stalling at trolling speed

went through a few things yesterday and thought i'd clean the spark arrestor and change the plugs and see what kind of differnce it made. after cleaning the arrestor it sounded much better. then i pulled the plugs and found that they were not at all the size recommended. i called the guy i got it from and he said that he ran them hotter so it would troll better. I figured this would be a good time to really see what this thing needs and followed your advice. yesterday afternoon we drove it up river to the boat doctor for a new carb kit and a tune up and (hopefully) a fresh start.

 

[karma]

Re: 260 mercruiser stalling at trolling speed

well guys, got her back this weekend and cant believe what a carb kit and tune up can do. We tested her out and she purrs like a kitten and gets all the way down to 1.8 (s.o.g) with no buckets or sea bags!! the mechanic said the timing was off 2.5 degrees? and the carb needed it. thanks again for your help