25 hp mercury power/fuel problems

floatmiboat

Petty Officer 3rd Class
Joined
Sep 4, 2010
Messages
90
Hi,
I have been having the following problem. Motor starts fine and runs, put it into gear and runs slowly, open up the throttle and it bogs down but won't accelerate, after five minutes or so it lurch a couple of times or not at all and then take off. After that it runs fine. Recently I had it out and after drifting for a half hour it died twice on start up and then ran like I just mentioned for five minutes or so until it took off again. I had thought it was water in my old metal gas tank however, I replaced the lines and tank before I took it out last. Any ideas on what's causing this to happen? Thanks
 

Traceyh

Seaman
Joined
Aug 16, 2010
Messages
66
Re: 25 hp mercury power/fuel problems

Check fuel line bulb for firmness when its exhibiting this problem. After that, the fuel pump would be my next suspect, maybe getting air into the system somehow, and not pumping effectively until it runs a few minutes and purges the air out of the system. Lastly, I would check carb low end settings, it could be extremely lean on the bottom end and wont accelerate until the engine warms.
(could also be slobbering rich). When it does kick in and take off, does it smoke alot, like it could be loaded up?
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,616
Re: 25 hp mercury power/fuel problems

Sounds more like a electrical problem such as a switchbox,spark plug or harness(box to coils) problem. From what you posted its running one one cylinder and then the other one kicks in. Do your basic tests,spark,compression,fuel sample....
 

floatmiboat

Petty Officer 3rd Class
Joined
Sep 4, 2010
Messages
90
Re: 25 hp mercury power/fuel problems

Hi,
Thanks for your ideas. I took out the boat this afternoon and had the same issues only worse. Drove it around the bay for ten minutes before it would take off. I noticed the motor sounds different kind of muffled until it kicks in and takes off. Didn't smoke or anything. Noticed that when it was running right and I shut it off, it bogged down again when I restarted it and opened up the throttle. Bulb seemed fine while running and it will rev up in neutral. I had the spark plugs, compression checked about 2 months back. It seems like it's not getting fuel?
 

floatmiboat

Petty Officer 3rd Class
Joined
Sep 4, 2010
Messages
90
Re: 25 hp mercury power/fuel problems

Couldn't figure it out.Seems to be an electrical issue. Took it to a mechanic today. Will post results.
 

floatmiboat

Petty Officer 3rd Class
Joined
Sep 4, 2010
Messages
90
Re: 25 hp mercury power/fuel problems

Finally got my motor back. The problem was warped reed valves
 
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