91 Yamaha 140hp no spark cyl 3?

[GoogieMan]

G'day guy's i have a YAMAHA 1991 140hp i am having trubble with no.3 cyl not fireing? i have tested all others and all are great.

The spark will return after a while anywere from 10 mins to an hour later depending on the day really.

1. if the overheat sensors get dissconnected does it affect the spark? one is faulty waiting on new one's

2. what could cause the spark to come and go only on one cyl?

3. i have swapped known working coils to that cyl still nothing

 

[99yam40]

Re: 91 no spark cyl 3?

Re: 91 no spark cyl 3?

read # 9
http://forums.iboats.com/showthread.php?t=250876

Not even sure what brand of motor you have. It is usually best to test things instead of replacing / swapping parts. Do you have a manual? it will give the steps and equipment for troubleshooting the different systems.

 

[GoogieMan]

Re: 91 no spark cyl 3?

Re: 91 no spark cyl 3?

read # 9
not even sure what brand of motor you have.

Sorry donk is a yamaha was running late for work. ok testing starts were? puls have been replaced not long ago same with Cdi

so im asking what could cause only 1 cyl to drop out mainly for the first 1 hour then return for the rest of the day? i here rodbolt is the yamaha guru

140CETO - 6F3

 

[rodbolt]

Re: 91 Yamaha 140hp no spark cyl 3?

then carefuly inspect the wiring into and out of the CDI and carefully test the pulser coil inputs and the CDI outputs and the issue is resolved.