115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

[985johnm]

my 1987 yamaha 2 stroke 115 hp v4 is only running on cyl numbers 2 and 4 numbers 1 and 3 are not firing. (I put a timing light on all four to find this out.) I swapped the wires that excite the coils with 1 and 2 and the coil for cyl #1 fires fine. So what do I need to check 1st to see why there is no power going to coils #1 and #3. thanks in advance john

 

[mobilemike]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

Either the pulser coil is not working or the cdi is bad.Test the pulser coil(s) first.

 

[985johnm]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

the motor sat up for 18 years. I disconnected the oil injection system and looped the float wires going to the oil injection computer.
1.Does limp mode on a 1987 just retard timing or does it shut down #1 and #3 cyl?
2. assuming it's the pulser or cdi could it just be corrosion on the inside of the fly wheel? Could that line up with loosing 2 cyl on the same side?
3. In my manual there is a generic picture of an ignition system it shows a 20 amp fuse in the equation could it be a fuse?

 

[mobilemike]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

rev limit shouldn't kick in during cranking, in any case,retarded timing wont cause a no spark. Didn't know that you had the O/I disconnected. Just for S&G, remove the float sensor from the tank and plug it back into the harness and position it upside down in the lower cowling and retest. 1&3 are on the same pulser coil, which sends the signal to the cdi to fire both coils at the same time. ohm the 2-4 pulser and compare readings to the 1-3 pulser.They should be close. My later model tune up guide says 320 ohms,but as long as they are close to the same,pulsers are probably ok. I'm digging out some older manuals and will have more info later today.

 

[Ballymac]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

Agree with mobilemike - probably your pulser coil. Make sure you check all of your connections & wiring. That long of a lay-up is brutal to your electrical systems & ignition. You'll need a peak voltage meter to check voltage in & out of the CDM.

 

[985johnm]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

pulser coil ohm both very simular around 320 ohm. charge coil ohm brown - red dead on at 1052 ohm black/red and blue leads ARE WAY OFF AT 128 OHM should be 24 +/- 20% . With this could a bad charge coil/stator assembly create a problem that the 1 and 3 cyl don't fire? is this my problem?

 

[99yam40]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

Yes that would indicate a bad assembly unless there is a bad connection going to it

 

[985johnm]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

what do you mean bad connection going to it? the charge coil , pulser/trigger are disconnected when being tested with the ohm's meter.
and can a faulty charge coil be reponsible for loosing 2 cyl?

 

[99yam40]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

Sorry, you are right the lower ohms would indicate a short not a bad connection if the specs are not met and there are not other connections between. But there could be bad insulation or a pinched wire in there

 

[985johnm]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

thanks for every ones help so far! My ohms are higher than recommended what does that mean? and do I need to change the pulser coil or the charge coil or both based on all the information above? I need to know if I should spend $400 or $800?

 

[99yam40]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

See what a few cool ones will do to my eye sight and reading ability late in the evening, sorry again:facepalm:

I would take voltage readings with the proper test equipment just to be sure. Ohms is just one of the trouble shooting tools

My thoughts are that you have a low speed and a high speed charge coil and all cylinders should be affected not just 2 of them if one of them is bad, but as you can tell I may not know what I am talking about some times.

 

[985johnm]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

I was looking at the wrong ohms chart. My charge coil is great! I then tested my cdi box and it was way off. It would read ohms then nothing and when it would read nothing I would push hard on the box and it would read crazy stuff and sometimes correct ohms. I figure I have a short i the cdi. Which supports your theory of charge coil and pulse coil good or not good. I ordered another cdi it was $415

 

[1Crazymechanic]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

It sounds like bad cdi, post when you get it installed and let us know how it does.

 

[985johnm]

Re: 115 v4 yamaha no spark 1&3 cyl but both ignition coils are good?

cdi was the culprit. cheapest one was $415 with shipping on ebay. Hooked it up and all 4 are firing now. I'm gonna do a link and sync tomorrow and then adjust my carbs. Thank you to all the people who replied this problem could have cost way more if I'd replaced multiple electrical parts.