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Mercury 70 hp misses and wont idle

randy_h

New member
"started on muff engine runs o

"started on muff engine runs ok at half throttle on cold start,but when throttle is backed off engine misses and dies.carbs have been cleaned but no difference.i did notice that when i pulled number 3 cylinder plug wire off engine ran the same as if i didnt take plug wire off.150 lbs compression on all 3 cylinders.any suggestions as to what i should check.thanks"
 
Check for a " strong "

Check for a " strong " spark on #3 cylinder.Remove the spark plugs and crank it over with a rope and listen for a steady crankcase compression.
 
"1983 3 cyl,not getting fire o

"1983 3 cyl,not getting fire on #3 switched coils still no spark on #3.could it be the switch box?"
 
"Randy,

Could be either the


"Randy,

Could be either the switchbox or the trigger. You should have four wires from the trigger; white/black, purple, white and brown. Check the resistance from white/black to each of the other three wires. You should read 750-1400 ohms. If the resistance reads good check for voltage at the three terminals on the switchbox where these wires connect. You should be able to detect something even with an ordinary multimeter. If you get any reading, the switchbox is probably bad, but if the trigger is bad, it is a good idea to replace both anyway.

Tony"
 
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