96 150 mercury floods

fish brain

fish brain

Crew Member
I have an old merc 150 outboard which has a tendency to flood when cold or cool. I asked Deans Marine in Duncan to look at it last year. The mechanic said to burp the oil tank after a wide open run. it seemed like a dumb fix but I tried it. Doesnt work. I suspected a bad float, I have pulled all the carbs off, cleaned and tested them and they seem fine . No difference after cleaning in how the floats seem to seat.
Does anyone have any suggestions?
 
The boat runs fine once it has warmed up. no sputtering or hesitations. thus my thought that it might be a bad float.
 
Shot in the dark, the float needle worn out. Doesn't seat well till it gets warm? Blows thru slightly.
 
Thanks for the thought Bones.
I have bench tested the float by turning the bowl upside down and blowing through the intake as hard as I can. I can't make ant of them leak air, so I am assuming that they are seating properly. Am I going about this the wrong way?
 
When is tis happening year round or just winter use when cold?
 
It happens year round.
It started in 2015. It seemed to be when I tried to pump the primer bulb to hard, so I got to the point where i just tickled it. (another reason to think it was/is a float problem) It got worse last summer. I can always get it going, but I worry that eventually it will just not start. I do carry extra plugs for such an event, but I'd prefer to have more confidence in the motor.
As a side note. when I pull the plugs they all seem to be wet, so that maybe points away form the floats?
 
Had a 115 Merc tower of power, was always easy to flood first start of the weekend.
Perhaps check cranking speed and voltages.
 
Thanks Wild Bill I do a load test. But it seems to crank over fine
 
I didn't bother fixing anything on mine, just first start of the weekend was tough. sometimes tilting to drain carbs and crank to clear and start. Just seemed slower crank when it happened. As long as you used it daily it started fine.
 
Could it be a choke problem? It's been a long time since I had a carbed motor but at one point I had a choke issue that caused a similar symptom. How's the compression?
 
Wild Bill said:
I didn't bother fixing anything on mine, just first start of the weekend was tough. sometimes tilting to drain carbs and crank to clear and start. Just seemed slower crank when it happened. As long as you used it daily it started fine.
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Starter seems to check out fine. thanks for the thoughts
 
uclueletcharters said:
Could it be a choke problem? It's been a long time since I had a carbed motor but at one point I had a choke issue that caused a similar symptom. How's the compression?
Click to expand...
The compression is lower than I'd like to see it 110-115 across the board, no cylinders vastly out of wack. Maybe it's the problem. I am going to check the fuel primer valve for ***** and giggles just to be sure. I wont be able to get to that until next week sometime tho
 
Sorry for the late reply Hourstonglassic. The floats all look good, and most of the plugs seem to get wet. I have all the carbs off the motor. I hope to get them back on this week
 
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