2000 Merc 125: Does this sound familiar???

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baypilot

Recruit
Joined
Jul 25, 2003
Messages
2
Ran engine aproximately 2 1/2 hours Tues and Wed, no problems. Same tank of gas (1/2 tank left), same oil (about 3/4 tank left) different day, today. Engine initially fired up then quickly stalled, with alot of white smoke noted. Tried again, cranked up and advanced throttle quickly this time. Engine would not tach above 2200RPM, with throttle about 3/4. NOTE: This normally is about a 3500 RPM setting while under way. Still alot of whitish smoke running very rough, and stalled as soon as I thought of pulling throttle to idle. Changed out all 4 plugs, and noticed a large amount of oil on each. With spare plugs in, engine cranked right up again with same result. Very rough, not able to get RPM's above 2000-2200, alot of smoke and stalled out as soon as thottle started toward idle. WHAT IS WRONG? HOW DO I FIX IT? IS THIS A SITUATION TO BY :( :( PASS THE INJECTOR AND GO TO PRE-MIX?
 
T

The Marine Doctor

Commander
Joined
Jul 25, 2003
Messages
2,177
Re: 2000 Merc 125: Does this sound familiar???

Sounds like the carbs filled with oil...REstart the engine and continually PRIME it and see if it clears up.<br /><br />TMD
 
S

sharkcat

Petty Officer 1st Class
Joined
May 4, 2003
Messages
285
Re: 2000 Merc 125: Does this sound familiar???

Ill have to disagree with the marine doctor it sounds to me like you have an electrical problem on 1 or more cylinders.Check the spark on each/disconnect each plug lead in turn whilst the engine is running if there is no difference in the way the engine runs after you have disconnected a lead that cylinder is not working<br />Hope this helps
 
T

The Marine Doctor

Commander
Joined
Jul 25, 2003
Messages
2,177
Re: 2000 Merc 125: Does this sound familiar???

Upon rereading the post..and noting its a Merc :) not a Johnson with a bad VRO, have to stop bouncing around in the forum and pay closer attention.<br /><br />The engine is a 2+2 @ idle it runs on 2 cyls.<br /><br />Take note the engine will not run on 1 cyl.<br /><br />Therefore the problem lies in the 3-4 cyls. Either low compression or insufficient spark.<br /><br />As Shark has outlined...remove one lead at a time..when the problem is worse..you will know which cyl is the problem. It will be the opposite of the one that makes it worse.<br /><br />TMD
 
B

baypilot

Recruit
Joined
Jul 25, 2003
Messages
2
Re: 2000 Merc 125: Does this sound familiar???

I got the boat home and found out that it will 3 weeks before my local repair shop can get to it, so I decided to try and start it in order to flush the cooling system. While I was at it I disconnected the spark plug leads top to bottom. The RPM's were steady at around 1800. 1, 2, and 4 from the top to bottom changed nothing when plug off. 3 did cause the engine to run noticably rougher, but it did keep running. After I shut it down there was a large amount of raw oil noticable on the driveway. Also, while running it was still rough and smoking. All connections from oil tank to oil pump to fuel line look good. Any more ideas before I lose this to the boat yard for 3 weeks?
 
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