85 Merc 25hp bogging out...

[UNCC Grad]

I recently traded for an 85 Mercury 25hp 2 stroke that isn't running quite right. Basically it idles OK, but when you start to rev it up, it tends to bog down and sounds like it isn't hitting on both cylinders. Then, for no reason, it will kick back in and take off, then bog back down. For some reason it will not stay up to full throttle. When it does stay full throttle, look out, cause it pushes my 16' jon like a bat outta hell.<br /><br />What could be the problem here? I tried two seperate fuel lines with the same results and the gas is fresh and properly mixed. Any help is greatly appreciated.<br /><br />For what it's worth, I know very little about outboards, but have some buds that can help out if we can locate the problem.

 

[The Marine Doctor]

Re: 85 Merc 25hp bogging out...

From the sounds of it, you may have to take the carb off and clean it.<br /><br />TMD

 

[Elmer Fudge]

Re: 85 Merc 25hp bogging out...

Like TMD said you most likely picked up some dirt that is restricting the fuel flow.also check the fuel tank filter for a possible clog. Installing an inline filter between the tank and the bulb would'nt be a bad idea.

 

[UNCC Grad]

Re: 85 Merc 25hp bogging out...

We got it fixed last night, it ended up being that the ground wire to the power pack was corroded, which caused a spark to arc to the cylinder wall.<br /><br />We ran it for a while with clamshells on it and it was running great at 3/4 throttle until it just shut off, apparently for no reason.<br /><br />After trying for 20 minutes we got it fired back up and it idled rough, and then shut off. It also wasn't pumping water out the toplike it was before. Now we can't get the thing started back up. We pulled the plugs and the are sparking and fuel is still entering the carb, but it just won't start. Could it be that we just flooded it out?<br /><br />Could I have burnt a piston when running it with the clamshells on? What about not pumping water now?<br /><br />I hope I haven't ruined this motor. Thanks for the help.

 

[The Marine Doctor]

Re: 85 Merc 25hp bogging out...

It is possible that the loose ground wire did some damage to the power pack.<br /><br />3/4 throttle is a no no when it comes to the water muffs.<br /><br />You might want to check the compression as well.<br /><br />TMD