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1986? Mercury 25HP misfire or bottom cylinder not firing?

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NateZilla420

New member
New poster to the forum here... I have gone through the ringer on this, bottom cylinder not firing? I can unplug the bottom cylinder spark plug wire and idle does not change; unplug the top cylinder plug wire and the motor kills. It has new ignition coils, spark plug wires, and plugs, NEW SWITCH BOX(which I thought was the fix for sure), new fuel filter, new impeller and water pump kit, AND fresh lower unit oil change... When the motor is in forward it will not ramp up to full power, seems to bog through the water(probably the 1 cylinder’s power) In reverse gear the motor seem to be able to rev all the way up to full rpm. Could there have been a switch in re-attaching the shifter linkage causing the motor to only rev when in forward-to the reverse gear’s maximum rpm’s? Is that a thing!? I’m lost. Any advice/ direction would be greatly appreciated!
 
Nothing to do with a switch.-----It revs up in reverse because of all the exhaust in the water.----Less resistance for the prop.-----A cylinder needs 4 things to produce power.----Spark at the right time.-----Compression in the cylinder.----Correct amount of fuel.------Compression in the crankcase.-----So do a compression test and post your numbers.-----Does spark jump a gap of 3/8" or more on both leads ?------Could be a bad reed valve or leaking bottom crankshaft seal.-----Checked the fuel pump diaphragm ?
 
Awesome, thank you. As I am a novice, I appreciate any bit of help. I will post the results of my testing ASAP. My method of throwing darts at the board has obviously not been successful.
 
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