1999 c75tlrx Yamaha #2 cylinder no spark

[chris bayou]

my motor has no output from the cdi (#2 cylinder) at cranking speed or up to 2500 rpm it never kicks in .... i know this particular model runs on cyl.1&3 at idle then #2 picks up spark past 1450rpm. so far I checked coils and they are all good , checked crank position sender its dva is in spec, lighting coil ok, charging coil ok , I noticed the pulser coil only putting out 2.5v when it should be putting out 7v at cranking speed and when disconnected . could this be my smoking gun ? trying to hunt this weekend any help asap please!!!

 

[99yam40]

Re: 1999 c75tlrx Yamaha #2 cylinder no spark

Never heard of a 3 cylinder designed to run only on 2 at idle, but that shows what I know about a 75.
Post the DVA readings you got when testing at cranking and running.
This includes inputs and outputs of the CDI.
Charging coil and pulsar coil should be the sparking system
lighting is for charging battery

Does this have two charge coils one for low speed and one for high?

 

[robert graham]

Re: 1999 c75tlrx Yamaha #2 cylinder no spark

Does your #2 spark plug look wet/fouled? The fuel pump runs off of that #2 cylinder and if the pump diaphragm is bad it'll suck raw gas into that cylinder and wet-foul it with gas. Remove pump(2 screws), leave it hooked up to fuel hoses, pump primer bulb and check for gas coming out the back of pump. New pump is $50....Good Luck!

 

[chris bayou]

Re: 1999 c75tlrx Yamaha #2 cylinder no spark

all measurements taken at cranking speed .....my charge coil outputs measure: red-brown=55v, red-blue=90v which is all in yamaha spec according to the repair manual, yes it does have 2 low and high

my pulser coil output white\red-white\black= .2v yamaha service manual states it should be 7v at cranking speed

cdi output @ cranking speed- cyl#1=105v, cyl#2=0v, cyl#3=105v @ 1800rpm same readings

I also did a cylinder drop test while running and on the hose running @idle all the way to 2500 rpm on Cyl.#2 I pulled the plug cap and no change in running performance Cyl. 1&3 changed the performance for sure seems to me the spark will never come in on that #2 cylinder and i wasn't sure if that pulser coil would indeed affect the #2 cylinder only... keep in mind the motor runs perfect @idle -1250rpm in water or on hose

 

[99yam40]

Re: 1999 c75tlrx Yamaha #2 cylinder no spark

From what I under stand The pulsar coil tells the CDI when to fire , so I am not sure how this thing is firing 1 and 3. Seems like I read some where that the 90 used the pulsar to fire one cylinder, but not sure.
But probably need to get the pulsar coil fixed and see if that solves your problem.
You said 2.5 v and now .2 v which was it?

On my C40 TLRX Yamaha manual
at cranking (minimum peak voltage)
pulsar is 3 volts
Charge coil 145v
CDI out 125v

Are you using a DVA adapter with a regular meter?

If you are not using the proper volt meter you will not get the right readings.
Your charge coils readings sound low, but if your manual says it is within spec I guess it is OK

 

[pearse clark]

hi did u find out what your prob was as i have the same prob and i changed cdi box which cost me 1400 euro and still the same,post back when u get a chance ,regards,pearse