1987 Yamaha 90 ETLJ pulser test valid?

[Dank]

Hey Folks,
My #3 cylinder has very weak spark, and seems to only fire once RPMs get up around 4000 or so. Tried swapping coils & plugs, but problem stayed with #3. Seloc manual has resistance test that states 1 pulser should read 350-420 ohms resistance, while the other pulser should read 800-900 or better (wht/blk to wht/grn). I'm showing just over 300 ohms for both pulser coils. I was convinced that is my problem until I read a comment Rodbolt made to someone else suggesting that #3 wasn't controlled by a pulser. Did I misinterpret? I don't have a DVA, so I'm limited at this point to resistance tests. The other tests in the ignition arena seem to all be within spec. Any thoughts as to the validity of the Seloc test and whether it would even affect the #3 spark? Thanks, Dank.

 

[rodbolt]

Re: 1987 Yamaha 90 ETLJ pulser test valid?

according to the tune up spec guide the 84 to 93 90HP motors the pulser coils control 1 and 2, and 3 is made up by the CDI unit.
according to said guide both pulsers should be about 330 ohms.
try setting your meter on AC volts and compare the CDI output for all three ign coil primary inputs(CDI out).

 

[Dank]

Re: 1987 Yamaha 90 ETLJ pulser test valid?

Thanks Rodbolt, I appreciate your time and knowledge. Do I test the AC voltage while cranking with the plugs out or while running? I assume I just check across each ignition coil wire and the CDI ground wire? Thanks, Dank

 

[rodbolt]

Re: 1987 Yamaha 90 ETLJ pulser test valid?

while running go from the ign coil primary,blk/white to ground.

 

[Dank]

Re: 1987 Yamaha 90 ETLJ pulser test valid?

I couldn't get any reading with my meters on the output to the coils. Got less than acceptable results while testing the stator outputs, but I don't trust my el cheapo meter. I've ordered a better meter and dva adapter so hopefully I'll have better luck. I'll post back after I try again. Thanks, Dank.

 

[Dank]

Re: 1987 Yamaha 90 ETLJ pulser test valid?

What a head-scratcher...
I got a ESI DMM, (480a) and the partner DVA (ESI 640). Ran the gamut of resistance and voltage tests. Resistance numbers all looked good except blue to red stator test was a bit high at 141 ohms (65-130 acceptable range according to CDI guide). DVA voltages from stator coils and triggers were well above the thresholds. After that things got weird. When moving to the coils, I got extremely low DVA voltages to each coil... to the tune of 1.7, 1.9, and 1.4 volts. The numbers are with the engine at idle. They creep up a couple of tenths as I raise the RPMs to 1500 or so. According to the CDI guide the DVA voltage should be at least 125 volts. I find it hard to believe that the engine would run with that little voltage getting to the coils. I checked the DVA against household voltage and 12 volt DC voltage and it checked out fine, but I have to think something is wacko here. I called ESI tech support, who offered to check the meters out if I send them in, but if it's EMI interference or something causing the problem, the're not likely to find it. I'd be interested to hear if anyone has any ideas! By the way, I'm testing from the blk/wht wires going to each coil to ground. It makes no difference (as expected) whether my ground is on the engine block or the ground terminal of the switchbox. Thanks, and sorry for the long post!
Dank