NO SPARK 1972 JOHNSON 50HP

thouse

Cadet
Joined
May 24, 2015
Messages
10
Hello,

I am new to the forum here , and just wanted to say thank you to everyone for offering their knowledge , tips , and advise when it comes to working on these outboards. I used your forum to diagnose and get my old 1972 johnson 50hp running that I purchased with boat for dirt cheap.
My problem now is , I went through the CDI troubleshooting guide the other day for when my 50hp johnson was not sparking. I went through the steps and found out that it was a combination of rectifier and kill wire. I replaced rectifier and repaired killswitch wire and she was sparking and running good in the rain barrel!

When i took it to the lake , it did not want to rev out in forward gear , so i returned to the dock. At the dock I was making more adjustments and bumped it into gear when it was idling high. I then instantly shut it off to avoid hitting the dock. This is where my problem now lies , After trying to restart the motor I am not getting spark again! I went through the same CDI troubleshooting steps and still no spark.

Can anyone offer any suggestions? I used my multimeter to test stator and on the 2 yellow leads i got a reading of 1.8 , and then when i touched a lead from brown wire , and then the other lead to the powerhead for a ground i got 0. Would this not indiacte that the stator is fine? Also if i pull the coil orange wires off the powerpack and stick my test light in the screw hole in the powerpack and then have it grounded to the powerhead it flashes that power is going through.

Would a coil just suddenly fail? let alone both coils?

Any help would be greatly appreciated.
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Do you mean a zero or a infinity? Zero would mean a dead short on the stator to ground.
Have you tried undoing the killwire again?
Lucky you were by the dock:watermelon:
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Not reving up can be due to bad compression so you should check that, and that spark jumps a 7/16 gap (when you have it going again). Weak spark wont ignite fuel in the cylinder
 

thouse

Cadet
Joined
May 24, 2015
Messages
10
Cold compression test revealed 130 top , 110 bottom. As far as the not revving out in forward , i believe my spark advance was not moving in sync with the throttle as the plates on the carb were opened , but the advance did not move very far. I am away with work this week , but I think when I get home I will start by removing the flywheel and testing everything. I put 1 lead on the brown stator wire then a probe to the metal on the powerhead , and it read 0. The other readings were 1.8 on yellow wires. Can a stator suddenly fail? Boat was running and then all of a sudden nothing. Recently replaced the rectifier as that caused a no spark in the first time.
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
if the wire gets rubbed out it will short to ground and suddenly cut the motor. they often get worn where the timing base harness swivels and the wires get dragged along the crankcase
 

thouse

Cadet
Joined
May 24, 2015
Messages
10
Ok i am heading back home fRiday so I am going to pull flywheel and check out parts
 

thouse

Cadet
Joined
May 24, 2015
Messages
10
Just wanted to give an update. I have tested sensor coil , stator , charge coil wires all read back with normal OHM readings. When i pulled the wires going to the coils (2,3) i believe on power pack (orange) and stick my test light probe in the hole the test light flashes when engine is being cranked over. However , when I connect the orange wires , and probe them and crank the motor i get no flashing. Seems to be when the coils are connected to powerpack they are not getting any power from it. Is there a way to test powerpack?
 

kingblazer84

Cadet
Joined
May 16, 2015
Messages
11
clip your test light to the terminals on the power pack where your 1 and 2 coil wires run to then ground the tip of the test light on the body of the motor and crank the engine over it should light up solid and bright if the power pack is good
 

thouse

Cadet
Joined
May 24, 2015
Messages
10
Thanks all for the tips , I have found the problem to be the Powerpack. I went to a guy who had a bunch of parts laying around and we swapped powerpacks and bam she fired right up! Now I have more problems....but I will search forums or repost new thread for that...
 
Top