lack of power

[Chris B]

Thanks for all the responses. This is what I have so far:1) If the engine idles at full rpm then it shouldn't the mixing elbow or a clogged exhaust.2) Improper prop pitch or some other kind of drag on the boat could cause this problem. The prop and shaft are clean. The bottom is clean. The prop is original, and the stuffing box is leaking slightly. Can the prop pitch be off? If so, how do I know? If there is drag in the stuffing box, will repacking help?

 

[Justin/PYI]

Pitch and RPM

It isn't a guarantee that the engine is all well just because it will run up to full rpm out of gear. It takes much less fuel to accomplish this than it does under load. It is one indicator, but not the only indicator.If we "assume" the engine is fine and the pitch might be the culprit then the obvious indicator is if you can not reach max rpm (3500-3600) while motoring in flat water with clean bottom then you are overpropped or overpitched. Yes you can have the original prop and still be overpropped. Why I don't know, but it is much more common than we'd like to think.

 

[Harry Asbury]

Something else - Maybe

Chris I have a 1GM in my 27' and had/have a similar problem. It took me almost a year to find it. When I would start my engine it would run fine, go to full rpm, 3000 for my boat and prop (I'm over pitched and know it) and run that rpm for 20 minutes and then drop to 2400 and then to 2200. Would run at that rpm for the rest of the day. The engine did this every outting. I changed fuel, filters, the whole nine yards, still no different. Two weeks ago my wife and I went on a seven day sailing vacation, a couple of days before we left I put both batteries on charge with a new charger, made sure they were fully up. The first day out the engine ran full rpm no problem. The second day it ran fine until the wife turned on the refrigeration to help keep the ice frozen. The rpm dropped to 2400, it took me awhile to make the connection, but when I turned off the reefer within five minutes the rpm came back up. DAHHH!!On our other sailing days it takes us ten to fifteen minutes to get from our slip, down channel and out to the bay, as we travel out to the bay the reefer is not on, but once out we turn it on to help keep the ice from melting so fast. Plus, we only run the engine about an hour total on most days, not enough to keep the batteries fully charged. But we go out two or three times a week so the batteries never go down enough to put on shore charger. The bottom line is the added power load was dragging down the rpm. I would think that with 2GM it wouldn't be effected by the alt. as much as my engine but you never know.So if you have checked everything else look at how you sail and what you do and you might find the answer.