1989 Johnson got 150 spark issue

[Kymc3000@gmail.com]

Ok I got a good one, I have a 1989 Johnson gt150 that I just picked up to repower my boat. Issue is the engine doesn't have spark. If you remove the plugs from the cylinder head and hole the plug on a head bolt it has spark but when you put the plug back in the cylinder head the spark is gone??? Checked all grounds and wire connections, even tried running new ground to cylinder head but no luck. I don't know where to go from here, I'm a diesel mechanic and not to savy with 2 strokes. Any help is much appreciated
Thanks kyle

 

[Faztbullet]

Sounds like dragging starter as needs min 300rpm to produce spark

 

[Kymc3000@gmail.com]

Thanks for the response faztbullet, that could make sense. My cranking RPMs were about 290 with all the plugs in and the starter was getting very warm. Does anyone know what cranking RPMs should be?

 

[racerone]

Classic case of slow cranking I believe.------Take the starter apart and inspect brushes.-----Post the ohm reading from shaft to commutator, should read infinity.-------Have battery load tested.---Inspect battery cables too.--------It needs to " crank fast " to generate spark.

 

[Kymc3000@gmail.com]

Thanks for everyone's help, I will check battery and cables tonight.

 

[Kymc3000@gmail.com]

Just an update, I replaced battery and cables. Still same issue, put a photo tach on the flywheel and cranking speed is 161 RPMs. Gonna replace starter and solenoid soon as they arrive.
Thanks for everyone's help

 

[Kymc3000@gmail.com]

Installed new starter today and fired right up. Thanks for everyone's help

 

[Big Gee]

Thanks for posting your results.