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1985 Merc 50hp 4cyl loss of power

L

lund175

New member
my merc 50 hp starts and runs fine for a couple of runs across the lake (3-4 minutes each) then will start to bog down and lose power to the point I have to operate at just above idle. I feel this is heat related possibly ignition but just wanted to see what feedback the forum had to offer.
 
Things you need to do.-------First check or install a new impeller.------Many folks neglect this.-------Have someone operate the manual fuel pump when motor falters.-----Test run with another tank and hose.-----Test and see if spark will jump a gap of 3/8" on all leads on a test device when motor falters.------Check for blockage in exhaust tuner.
 
racerone said:
Things you need to do.-------First check or install a new impeller.------Many folks neglect this.-------Have someone operate the manual fuel pump when motor falters.-----Test run with another tank and hose.-----Test and see if spark will jump a gap of 3/8" on all leads on a test device when motor falters.------Check for blockage in exhaust tuner.
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Thank you, It does have a new impeller. I will work on the other items you have mentioned and update the thread.
 
It might be fuel starvation. Is the vent to the tank open? And when it does this, does pumping the bulb make any difference?

Jeff
 
Thanks Jeff, I have checked the vent and it seems fine. I have not tried pumping the ball. I will try that next time I have it in the water. Hopefully in the next couple weeks.
 
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