2006 1200 no spark on cyl. 3 possibly also no fuel.

[CDNVmax1200]

Hello just seeing if anyone has run into this it's a little weird. I have no spark on cylinder 3, I swapped the coil pack and wire/boot with cylinder 1 and it fires ok. Also tested coil at 3 Ohms. Power to connector is good and this is where I'm unsure if this is a valid test or not but I place a Noid lamp on the connector to the offending coil and I am getting a trigger signal to the coil. I tested for spark with a timing light and pulled the plug and tested with a gap tester set at 0.6mm good on 1,2 and 4 nothing on 3. Now the plug was dry and I drained the bowl on #3 carb and there was some crap that came out, so I may have a fuel issue as well but if it was just fuel I should still have spark?
Anyone have any ideas or has seen this before?

Thanks,
Chris

 

[02GF74]

You've measured resistance of the LT coils (3 ohm), but how about HT coil resistance?

If you cannot get to the front coils, then you can measure from the spark plug electrode.

From memory that should be around 33 k ohm ( 14 k for coil, 10k for cap and 10k for the spark plug: both cap and plug are resistive type).

Also you may have bad contact between coil and lead, the leads I believe are wire so can corrode, cutting 5mm off the lead exposes clean wire.

 

[CDNVmax1200]

I did pull the wire and cap off and tested it against #1 cylinder they both measured just under 9K ohm, I'll measure the HT side of the coil when I get home. But I did swap the entire coil assembly between #3 and #1 and still no spark on #3 so the coil and I would assume is ok if it fires when swapped over to #1?

 

[02GF74]

so to summarise
- no spark on cylinder 3
- using noid - this is a LED connected to the coil trigger - you can see coil 3 trigerring
- swapping over coil 1 to position 3 gives no spark on 3 yet you measured coil 1 LT and HT resistance to be in spec and coil 1 fires hence known to be good

That's strange.

Did you swap coil 3 to postion 1 to see if it gives a spark?

 

[CDNVmax1200]

Correct I tested coil #3 it seems to be ok, I have trigger signal at the coil Connector #3 and I swapped coil three to cylinder #1 and it fires but #1 will not fire when place in #3's position. It is very strange, I don't work on bikes on a daily basis but I am a ticketed mechanic in automotive and commercial truck that said I mostly work on diesel stuff. This is honestly giving me a bit of a complex, LOL. I am going to go through all the basics again tonight and see if I've missed something stupid.

 

[02GF74]

When you say fire, you mean no spark seen in the plug gap?

 

[CDNVmax1200]

Correct, no spark.

 

[02GF74]

In which case I have to query if the trigger for coil 3 is telling the truth.

I would connect an oscilloscope to see the signal, it switches to low to fire the coil.

Below is a photo of a multimeter with oscilloscopes connected to coil during cranking (I just happen to have taken this recently as sometime else is having problems getting the engine running)

 

[CDNVmax1200]

I have a scope here, I will check that as well. Thank you for the input!

 

[CDNVmax1200]

Ok so I went through everything again, once I had to ponder things a little more. I check with the scope and there is a signal there. But something seems off on the harness side but I can't put my finger on it. I did plug the #3 coil into the control plug for #1 and got instant spark so I can now verify the the #3 coil assembly is functioning correctly. I did also test the primary and secondary coils, 13k ohms and 2.7k ohms respectively.
I need to dig through some schematics to check the wiring to verify a couple of things.
1) Key of engine off the red/white strip has continuity to ground which I'm not sure if that's normal?
2) The trigger wire is the same color as the rear stop lamp switch and both come out of the same spot in the harness?
I guess its sorta head in a forward direction.

 

[CDNVmax1200]

Problem solved! A bunch of rubbed wires involving the grey tach wire apparently will mess up the #3 coil signal enough to not fire the coil. After looking at the scope I notice that the wave signal was not clean and more erratic looking than the sample provided by 02GF74 and in that I started chase down the harness all the way to the "I think" advanced timing module? Anyway thats where I notice the grey tapped in and chase then found the rub through. Clean the debris and did the peashooter on the #3 carb and in come fuel and we are back in business. Thanks for the help 02GF74 if I had tried the scope I wouldn't have noticed the weird signal! And lots of links to great resources on this forum.

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