2018 Yamaha 115hp Spark Issue

frustratedboater

Chief Petty Officer
Joined
Jul 10, 2007
Messages
498
I have a friends 2018 Yamaha 115hp 4-stroke that was running very rough and sporadic idle. I shut it down and conducted a spark test to see if any cylinders were dropping. Fuel is good and pumping fuel well. I tested the ignition and I didn't see any ignition spark. Went through he typical- kill switch is operational, neutral safety at the engine is making contact.
I Ohms tested the pulsor coil and got a 520 reading and believe it should be around 360 (+/- 72). Is this correct"
 
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99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,257
how did you check spark?
Are you not getting spart to any of the plugs or just some of the plugs?
you need to monitor the inputs to the CDI and the out puts to find out what is going on.

I do not have a manual for your motor,
do you so you can look at the specs
 

frustratedboater

Chief Petty Officer
Joined
Jul 10, 2007
Messages
498
how did you check spark?
Are you not getting spart to any of the plugs or just some of the plugs?
you need to monitor the inputs to the CDI and the out puts to find out what is going on.

I do not have a manual for your motor,
do you so you can look at the specs

I appreciate the reply!
I do have a marine 'quality' spark tester (it has an acrylic body and 8 ports). I just grounded to the block and plugged from top to bottom on one side. I did not see any spark on either of the plugs. Prior to that it was running choppy and seemed like it was dropping a few cylinders. The guy said that the motor was shaking violently on the water and would bog back down at 1/2 throttle.
The monitoring the inputs... may be a little above my abilities. Since it is a friend of mine I do not have that year manual. I only have a 95' to 04' Yam manual.. By chance, would the procedure be in a 04' to 2014 Suzuki manual? Sorry, not my wheel house..
 
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99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,257
I appreciate the reply!
I do have a marine 'quality' spark tester (it has an acrylic body and 8 ports). I just grounded to the block and plugged from top to bottom on one side. I did not see any spark on either of the plugs. Prior to that it was running choppy and seemed like it was dropping a few cylinders. The guy said that the motor was shaking violently on the water and would bog back down at 1/2 throttle.
The monitoring the inputs... may be a little above my abilities. Since it is a friend of mine I do not have that year manual. I only have a 95' to 04' Yam manual..

I have no idea, since I never owned a 4 stroke Yam
but I would think it would not be the same as a suzuki as far as specs but I could be wrong.
kills switch should take out all spark not just some

there should be stuff to charge up things and others to tell it when to fire the plugs
 
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