yamaha 70 no spark on #2

[the Lackster]

Looking for help with a spark issue. No fire at all on the #2 plug. Swapped the coil pack with the #3 and the problem stayed on the #2 cylinder. Both 1 and 3 are firing strong. Where do i go from here? Rectifier? CDI? Any help is greatly appreciated. Thanks

[boscoe99]

Test the CPS.

[99yam40]

from what Boscoe mentioned it sounds like that 70 is similar to the 90,
only 2 pulsers for 1 & 3, so the crank position sensor and CDI get together and decide when to fire #2

service manual should have the proper testing of the CPS

[the Lackster]

from what Boscoe mentioned it sounds like that 70 is similar to the 90,
only 2 pulsers for 1 & 3, so the crank position sensor and CDI get together and decide when to fire #2

service manual should have the proper testing of the CPS

Indeed, i checked the cps and it was within the margin of the yamaha spec. Beginning to look more and more like a cdi problem

[99yam40]

I would check all wiring connections too

[the Lackster]

I would check all wiring connections too

So i ended up putting it in the shop in the event that i bought a cdi and didn't need it. He diagnosed it and did end up putting a cdi on it. That fixed the spark issue but i still have the bogging issue. Put it in gear and give it throttle it just falls on its face. Wont go and will cut off if i keep pushing it.

[99yam40]

I worked on my BIL 50 that was doing that, all I found was the bottom carb main jet had some debris in it.

did not make any sense to me that would cause a bog and motor to die from just one jet being partially plugged, but it ran well after I cleaned the carbs

[the Lackster]

I worked on my BIL 50 that was doing that, all I found was the bottom carb main jet had some debris in it.

did not make any sense to me that would cause a bog and motor to die from just one jet being partially plugged, but it ran well after I cleaned the carbs

I was hoping that was my issue. Went through and had to replace one carb, didn't phase it. Trying to see of there were any other folks that figured out this ghost problem! Thank you for the reply 99yam

[99yam40]

have you replaced the plugs?
they are cheap enough to just try a news set
motor needs good compression ,good spark at the correct timing, and the proper fuel to air ratio to burn properly and create power to push the boat.

have you checked to make sure timing is advancing when you give it throttle?
induction timing light will show what the timing is doing and also show if each plug wire is getting spark thru it
everyone should have a good timing light

[ausnoelm]

My guess is the shop replaced the CDI on "suspicion" and it didn't fix the problem, charged you and you're back where you started, clean the carbs thoroughly, washing them and spraying them is NOT cleaning them, also as mentioned, make sure the timer base is moving with the throttle.

[99yam40]

well I guess we still do not know exactly what 70 this is you are working on.
what controls the timing?

[the Lackster]

My guess is the shop replaced the CDI on "suspicion" and it didn't fix the problem, charged you and you're back where you started, clean the carbs thoroughly, washing them and spraying them is NOT cleaning them, also as mentioned, make sure the timer base is moving with the throttle.

Im leaning toward timing. Before i took it tonthe shop I checked and was getting fire going to the cdi but nothing coming out. He i good people and will make it right as far as the cdi goes. I should have taken it to him sooner but i enjoy tinkering on stuff. I thought at first i had a bad coil back didn't make it out that easy. I cleaned the carbs throughly, replaced jets, and blew everything out good with air hose. Now, here is a question. The boat wont get past idle if i give it throttle but manually push the carb linkage it will try to dig off.

Guys i really appreciate the input!! Im trying to learn. Never know when a little bit of extra know how might help get me back to the boat ramp!!

[the Lackster]

well I guess we still do not know exactly what 70 this is you are working on.
what controls the timing?

Thats my fault! I thought i had listed that. Its a 1993 70 tlrr 2 stroke. Precision blend has been removed and i have been running premix for 12 years.

So far since this bogging started i have done the following

- new ngk spark plugs gapped to yamaha spec
- new fuel line amd primer
- tank drained and cleaned, fresh non ethanol
- carbs cleaned, jets replaced
- strainer removed and cleaned

[99yam40]

OK, it has a timing plate and linkage that should move as the throttle is opened.
Does it?
do you have a timing light to see what the timing is doing?

and what did this mean about checking voltage into the CDI ,having it there but not out?
what did it measure to be , what did you measure it with ,and and does it have the proper voltage now?
sounds like #2 is sparking now, correct?

explain better about the "The boat wont get past idle if i give it throttle but manually push the carb linkage it will try to dig off."
what linkage did you push?

[the Lackster]

OK, it has a timing plate and linkage that should move as the throttle is opened.
Does it?
do you have a timing light to see what the timing is doing?

and what did this mean about checking voltage into the CDI ,having it there but not out?
what did it measure to be , what did you measure it with ,and and does it have the proper voltage now?
sounds like #2 is sparking now, correct?


explain better about the "The boat wont get past idle if i give it throttle but manually push the carb linkage it will try to dig off."
what linkage did you push?

Dear lord i have lost my whole paragraph twice while typing!!

Ok, the arrow on the timing plate moves when you push the throttle, if its moving correctly or not i have no idea. I do not have a timing light.

- all i had to check with was a klein multimeter. I dont remember the exact reading on the cps but it was within the range listed in the service manual. I was not getting any output to the #2 coil pack though. Yes, #2 is getting spark after the cdi replacement.

- the boat doesn't want to rev up even with the prime start lever at the control but if you open the carbs buy pushing the linkage that connects the carbs it will rev up and i can see all 3 spraying fuel mix.

- this issue started a while back but was intermittent until recently.