Testing pickup on Yamaha prohauler - ATVs

Silly questions! Is this a kick or button start? Is there a security 'Dead' switch fitted to the ATV that you have left on? Have you changed the actual spark plug? Is the Battery fully charged? Turn all the other features off that you can on the ATV before you start it. This stops any other drains on the voltage at starting.

If you have not done any wiring repairs and this problem has just seemed to have developed , then I am guessing you have a live wire that is touching another wire or bare metal of the frame , handlebars or some wires are plugged into a wrong connection ! You can search the internet for a wiring diagram for your bike and should be able to find one for free ,but it will cost you time ! try a Yamaha motorcycle site where members have open forums or use google images just type in your bikes info model etc and add wiring diagram ! But if you own a motorcycle I would strongly advise you to purchase a workshop manual (it does not have to be a genuine Yamaha manual ) as there are manuals for most bikes and the reality is that you should be able to make a huge savings on maintenance and DIY repairs, adjustments etc and with the full wiring diagram that you can follow and relate to will simplify any wiring problems in the future .

test: plug, spark plug cap, coil then stator pickup coil.

coil, kill switch has grounded itself, pickup coil gone bad, etc. grab a multimeter, a service manual and start testing things.

put an insulation screw driver in the wire end that connects to the cap, obviously disconnecting it from the cap. Crank over and move metal part of screw driver next to some metal and you should see a spark coming from the wire to ground if coil is good.

I am sure you have replaced the ground wire. Start checking everything from the battery on. Make sure all fuses are good. Sounds like it was jumped from a car, worse thing you can do especially it it is running. Could just be the coil. If not, cdi possible too. Are you getting power to all of your lights and everything now just no spark? If you can find a donor coil to check, make sure all of your grounds are good to the motor too. Google for testing specs on that model for the cdi.

you'll need a multimeter and service manual to tell you what wires to check and what resistances to expect. its pretty easy to do.

check your pickup coil?

There is no voltage specification listed in my manual but it does specify that the charge coil resistance test should be between 270 - 330 ohms and the pulse(pickup) coil should test from 171 - 209 ohms, figures listed are for coils around room temperature of 20 degress celcius

Yamaha ignition coils never go bad. It is probably the Stator/ Pulser coil (very common). You can check them with a ohm meter. You'll need the readings from a Yamaha dealership. The CDI box is very seldom bad But there is no checks that can be done on it. If everything else is fine ---than Yamaha says it must be the CDI box.(Rare)