2007 Grandvista 250 will not start

[garyv]

Engine turns over but no spark.   Here's a little background first.  The scooter has sat for 3 years due to health issues.  We're past those issues now so it's time to get it running again.  Even though it had stabilizer in the fuel, I pulled the fuel tank and drained the old fuel and added fresh.  I changed the spark plug, fuel filter, and air filter.  It started and ran on the center stand.  I changed engine and rear drive lube and ran it again on the center stand.  It started easily.
Then, I decided to do additional maintenance.  I replaced both tires, brake pads, changed the brake fluid, and coolant.  Replaced the battery.  Then I put all the plastics back on and now it won't start.
I lay the plug on the engine and crank it over but no spark.  I used vice grip pliers and clamped a heavy wire on the plug and grounded the other of the wire at the battery.  No spark.
I have jumpered past the rear brake switch and the side stand switch.  The fuses are good.  I have batt voltage at the red wire to voltage regulator.  I have battery voltage at the black/white wire at the coil.   I am not sure what I should have at the green wire to the coil.  The kill switch at the right grip will turn my test light off and on when checking at the coil.
Anybody have any ideas?

[garyv]

Oh, one more thing.  Even though it was new, I had put the battery on a maintainer for 24hrs before trying it out

[garyv]

Still having trouble with this.  I did test the coil primary and secondary and both ohm tests are good.   The next step in the service manual is is to check the exciter coil resistance.  It tells me to check between the black/white terminal and ground.  I cannot find a black/white wire at the "A.C. Generator connector".  I went to the next step and that was to check the resistance of the pulser coil.  That checks ok.  Anybody have an idea where this black/white wire is?  There are the three yellow stator wires and the two for the pulser coil coming out of the right side of the engine near where the stator is located

[garyv]

There are black/white wires on the other side of the frame.  They feed power to the cdi and the ignition coil.  They are fed by the ignition circuit fuse via the ignition switch.  I have battery voltage at all points along that black/white wire with key on and also when cranking the starter.   
It appears I still need to ohm test this exciter coil to eliminate the stator as a possibility.   If that is good then the only thing it appears it can be is the cdi box.
Of course nothing at this point can explain why this scooter ran with the plastics off and then I lost spark after putting it back together.  And now I have all plastic off and still no spark.

[garyv]

Ordered and installed a new cdi tonight.  Still no spark.  Pretty much has me stumped.  Any ideas?

[MJR]

What triggers the CDI? There should be something.

[mrbios]

First, CDI's almost never fail unless abused in some way by overheating or shorting or very high miles > 30 to 40K+.  No moving parts, just solid state circuits sealed in epoxy. 

The first step in a scooter no start (no spark) is to squeeze each front brake lever independently and verify that the rear brake light comes on.  But because you aid the motor does turn over those contacts are fine.

--> Bypass: in your case you said the scooter ran on the center stand then stopped working so I would check the spark plug wire, and any related ign wires that might have gotten disconnected or damaged.

Next is the kill switch - if it is not working (pretend it is in the off position) the motor will turn over when the brake is squeezed but not start this is most likely your problem.

Next is the kick stand kill switch - if the kickstand is down the scooter will turn over but not start (again no spark). This is possibly and issue.

Last or First ... your battery must be fully charged - a shortcut I recommend when in doubt jump the battery to a running car to get maximum power.

Hope it helps, any updates?

[mrbios]

What triggers the CDI? There should be something.

The CDI is triggered by a sensor on the crank shaft - the CDI is a hall effect coil that has continuous 12v power.  When the power is interrupted the magnetic field collapse and that caused it to issue a high voltage spark to the spark plug.  You can watch diy testing on youtube.

[garyv]

Thanks for the thoughts mrbios.  The kill switch works because I can see battery voltage at the ignition coil until I switch it to kill.  I can switch it on and off and watch the voltage come and go.  I disconnected both safety switches on the brake and side stand and jumpered around them.   The brake light was staying on but I have since removed it as I have stripped all plastics off in order to trace wires.
There are ohm readings in the manual to measure between the two terminals of ignition coil and also from a terminal to the end of the plug wire.  Both tests are in spec.
The battery has been fully charged.  It is new but I keep it on a maintainer when i am not working on it.  The monitor does switch from charging to maintenance. 
The service manual provides an ohm reading spec between the two wires to the pick up at the stator.  It is within the spec.  Is there another test I should be considering?

[MJR]

The CDI is triggered by a sensor on the crank shaft - the CDI is a hall effect coil that has continuous 12v power.  When the power is interrupted the magnetic field collapse and that caused it to issue a high voltage spark to the spark plug.  You can watch diy testing on youtube.

Exactly, I rarely see people mention it. If the CDI has power and a ground and the sensor is sending a signal then the coil should be triggered.

[mrbios]

You're welcome and sorry to hear you're facing such a frustrating problem there's nothing worse than electrical issues.  If done good work to isolate the problem. The next thing you could check is the pickup coil and that wire basically the thing that reads the crankshaft as it rotates and tells the CDI it's time to fire. If it's not getting a pulse the CD I won't fire.  you could also watch a YouTube video like I said take the CD off and test it on the bench by giving it 12 volts and then interrupting it very rapidly to simulate the crank sensor if it fires a spark it's probably good if it doesn't then you know you found the problem. If you live near San Diego I would test your CDI on my scooter to see what happened we could swap components until we found the problem

Thanks for the thoughts mrbios.  The kill switch works because I can see battery voltage at the ignition coil until I switch it to kill.  I can switch it on and off and watch the voltage come and go.  I disconnected both safety switches on the brake and side stand and jumpered around them.   The brake light was staying on but I have since removed it as I have stripped all plastics off in order to trace wires.
There are ohm readings in the manual to measure between the two terminals of ignition coil and also from a terminal to the end of the plug wire.  Both tests are in spec.
The battery has been fully charged.  It is new but I keep it on a maintainer when i am not working on it.  The monitor does switch from charging to maintenance. 
The service manual provides an ohm reading spec between the two wires to the pick up at the stator.  It is within the spec.  Is there another test I should be considering?

[garyv]

It was a tough decision but I have decided to take this to the local dealership to see if they can figure it out.                                                                                         

[MJR]

If you were close to me I'd be glad to help but I understand if your not and need the dealer to fix it. Let us know how it goes.

[garyv]

They called me and said the CDI is bad.   I decided to have them replace it and the burden of correct diagnosis lays with them.  They had to order one and it should arrive this week.

[garyv]

Well, the dealership replaced the CDI and still no spark.  Now I’m waiting for them to diagnose it again