Not getting spark

J_A_S

Cadet
Joined
Aug 18, 2019
Messages
11
Hey y’all new guy here, I recently got what I believe is a 1989 Mercury 80 hp s/n 0B301950 and I took it out on the water and it was doing great (aside from being hard to start at the ramp) until towards the end of the day it was struggling and bogging down to get up into the higher rpms so my first inclination is to clean the carburetors. Got the carbs cleaned up and it seemed to be running pretty well. Then the next day I hook it to the hose again to see how she’ll crank up from cold and now it won’t start at all. I replaced the spark plug and still couldn’t get it to fire. To rule out any carburetor fault I shot some starter fluid down the carb barrel and still no fire. So that leaves me pretty certain that my issue is I’m not getting any spark.
 

flyingscott

Fleet Admiral
Joined
Apr 8, 2014
Messages
7,985
Do a compression and a spark test. Are you sure the motor was not overheating?
 

J_A_S

Cadet
Joined
Aug 18, 2019
Messages
11
I don’t see why it would be. I just replaced the water pump and it had a strong discharge stream. I’ve been meaning to get a spark plug tester since you can’t really visually check spark on these type of of plugs. How much compressions should I be looking for?
 

J_A_S

Cadet
Joined
Aug 18, 2019
Messages
11
I did a compression test this morning and each cylinder had around 100 psi. The interesting thing was after doing the bottom and moving too the middle cylinder, the motor tired to fire up and by the time I got to the top cylinder, I had to cut the key off to shut the motor down. So I pulled it out and hooked it to the hose and then its the same story and it would not start
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
Take starter apart for inspection / new brushes / ohm test.----Have your battery load tested.-----I am not there to hear or see your motor.---It seems to me that it is not cranking fast enough to generate a strong spark.------The usual answer to the above is ---" my motor cranks just fine "
 

reynold460

Petty Officer 2nd Class
Joined
Apr 25, 2008
Messages
103
I had the same issue recently ended up being the stator and switchbox were both bad . research and do an ohm test on your stator would be a good place to start also you can unhook the two yellow wires from the rectifier to see if spark returns if it does stator is bad ! you can also unhook yellow yellow /black stripe wire from switch box to see if spark returns if it does you have a fault in the ignition switch circuit ! you can also ohm test the trigger ! this is allassuming you do not have spark
 

J_A_S

Cadet
Joined
Aug 18, 2019
Messages
11
I got a spark plug tester and I tried in plugging the two yellow wires from the rectifier and still nothing. So next I unbolted the yellow/black stripe wire from the switch box and still nothing. I do know this battery is not the best. It’s what came with the boat and no telling how ild
it is. It’ll turn over real slowly at first then gradually get better once the battery gets “warmed up” but the spark is driven by the stator so that shouldn’t matter anyways as long as it’s getting turned over at a decent speed (which it is) right?
 

J_A_S

Cadet
Joined
Aug 18, 2019
Messages
11
So I just noticed that the starter motor gear is alway in the up position engaged to the flywheel. Isn’t it supposed to retract up and down as the starter engages /disengages? Could it be possible that running it for an extended period of time with the starter motor engaged like fry something else? Seems kind of strange how it might fry some other piece of electrical equipment but not the starter itself
 
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