No spark 250 chinese quad
#1
05-27-2012, 04:31 PM
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No spark 250 chinese quad
The engine turns over, but has no spark I have replaced the coil, spark plug, CDI box and stator. I have followed other posts today and tested
Leave the CDI unplugged. Set your meter to measure AC volts on the 100 volt scale. Measure the voltage on the AC Ignition Power pin to the ground pin while cranking the engine. You should see 40 to 80 volts AC while the engine is cranking. What do you measure?
I had 0 Volts and tested the plug next to the stator and still 0 volts, what do I check next?
My CDI has to plugs on it 4 pin and 2 pins.
Leave the CDI unplugged. Set your meter to measure AC volts on the 100 volt scale. Measure the voltage on the AC Ignition Power pin to the ground pin while cranking the engine. You should see 40 to 80 volts AC while the engine is cranking. What do you measure?
I had 0 Volts and tested the plug next to the stator and still 0 volts, what do I check next?
My CDI has to plugs on it 4 pin and 2 pins.
#2
05-27-2012, 10:17 PM
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But is your 6 pin CDI DC powered or AC powered? You can't tell by looking. Your voltage measurements are not valid unless you have an AC powered CDI. Here is the generic procedure to see which CDI you have:
The 2 plug 6 wire CDIs come in two different designs. One is powered off 12 volts DC, and the other is powered off a moderately high voltage AC which comes from the stator. Unfortunately there is no reliable way to tell the difference between the two by just looking at them. To be sure you need to use a meter to find out which you have:
1) Unplug the CDI, and turn on the ignition. Do not crank the starter motor. Use a meter to measure the *DC* voltage on the pin labeled "AC ignition power" in the wiring harness to both ground pins in the 4 pin CDI connector. If you measure 12 volts DC then you have a DC powered CDI.
2) If you don't measure 12 volts DC on the ignition power pin, then switch the meter over to measure AC volts on the 200 volt scale. While cranking the starter motor, measure the AC voltage on the "AC Ignition Power" pin to the the Ground pin. You should see 40 to 80 volts AC. If you measure AC voltage when the starter is turning then you have an AC powered CDI.
Using a meter is the only 100% reliable way to figure out if your CDI is AC or DC powered. But there are some clues you can use that are usually (but not always) correct:
A) DC CDIs tend to be a little larger than their AC powered counterpart. This is because the DC powered CDI needs a bunch more circuitry to convert the 12 volts DC to the moderately high voltage supply that all CDIs must have.
B) Most (but not all) DC powered quad ignition systems do not use the kill switch input pin. The CDI connector pin usually has no wire tied to it. AC powered quad ignition systems usually do use the kill switch input pin.
1) Unplug the CDI, and turn on the ignition. Do not crank the starter motor. Use a meter to measure the *DC* voltage on the pin labeled "AC ignition power" in the wiring harness to both ground pins in the 4 pin CDI connector. If you measure 12 volts DC then you have a DC powered CDI.
2) If you don't measure 12 volts DC on the ignition power pin, then switch the meter over to measure AC volts on the 200 volt scale. While cranking the starter motor, measure the AC voltage on the "AC Ignition Power" pin to the the Ground pin. You should see 40 to 80 volts AC. If you measure AC voltage when the starter is turning then you have an AC powered CDI.
Using a meter is the only 100% reliable way to figure out if your CDI is AC or DC powered. But there are some clues you can use that are usually (but not always) correct:
A) DC CDIs tend to be a little larger than their AC powered counterpart. This is because the DC powered CDI needs a bunch more circuitry to convert the 12 volts DC to the moderately high voltage supply that all CDIs must have.
B) Most (but not all) DC powered quad ignition systems do not use the kill switch input pin. The CDI connector pin usually has no wire tied to it. AC powered quad ignition systems usually do use the kill switch input pin.
The engine turns over, but has no spark I have replaced the coil, spark plug, CDI box and stator. I have followed other posts today and tested
Leave the CDI unplugged. Set your meter to measure AC volts on the 100 volt scale. Measure the voltage on the AC Ignition Power pin to the ground pin while cranking the engine. You should see 40 to 80 volts AC while the engine is cranking. What do you measure?
I had 0 Volts and tested the plug next to the stator and still 0 volts, what do I check next?
My CDI has to plugs on it 4 pin and 2 pins.
Leave the CDI unplugged. Set your meter to measure AC volts on the 100 volt scale. Measure the voltage on the AC Ignition Power pin to the ground pin while cranking the engine. You should see 40 to 80 volts AC while the engine is cranking. What do you measure?
I had 0 Volts and tested the plug next to the stator and still 0 volts, what do I check next?
My CDI has to plugs on it 4 pin and 2 pins.
#4
05-28-2012, 05:53 PM
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I don't have the kill switch wire pluged in to rule this out, will it run without or do I need to ground the pin out?
I checked the coil to ground and have 1.1 ohms.
When I cranked the engine I have no AC volts from the CDI coil out.
I tested the AC for the trigger and my home tester is set at 200V (it's lowest setting) and get 0.1 volt
Thanks again Darren.
I checked the coil to ground and have 1.1 ohms.
When I cranked the engine I have no AC volts from the CDI coil out.
I tested the AC for the trigger and my home tester is set at 200V (it's lowest setting) and get 0.1 volt
Thanks again Darren.
#5
05-28-2012, 11:18 PM
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Since you don't have AC voltage at all going to the coil then we are down to a bad CDI, or the CDI isn't getting triggered. It's also remotely possible that the coil is bad, but this is less likely than the CDI.
Your measurement of the trigger voltage is 0.1 volts AC on the 200 volts AC scale. I have a few of those meters too. The resolution of your measurement is just one least significant bit, so it is subject to question.
Try this: Measure the AC ignition power voltage again with the CDI disconnected (you got 56 volts AC before). Verify that, then plug the CDI back in and measure the same voltage. Be sure to everything hooked up, the ignition switch on, and have all the kill switches set to the run position. Do you still get 56 volts AC, or is it a different voltage now?
Your measurement of the trigger voltage is 0.1 volts AC on the 200 volts AC scale. I have a few of those meters too. The resolution of your measurement is just one least significant bit, so it is subject to question.
Try this: Measure the AC ignition power voltage again with the CDI disconnected (you got 56 volts AC before). Verify that, then plug the CDI back in and measure the same voltage. Be sure to everything hooked up, the ignition switch on, and have all the kill switches set to the run position. Do you still get 56 volts AC, or is it a different voltage now?
#6
05-30-2012, 11:44 AM
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#7
05-30-2012, 05:42 PM
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#8
05-31-2012, 12:13 AM
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I checked the trigger voltage with a USB scope and got 1.6 Volt AC.
AC ignition power voltage with the CDI plugged in was 39 Volts AC and my Battery is dieing so it's now on charge.
I don't have the Kill switch wire connected to the CDI, would this stop it working?
Darren.
AC ignition power voltage with the CDI plugged in was 39 Volts AC and my Battery is dieing so it's now on charge.
I don't have the Kill switch wire connected to the CDI, would this stop it working?
Darren.
1.6 volts? Is this peak voltage (above zero), or peak to peak voltage?, or the RMS value (displayed as text on the display)?
How does your measurements compare to this:
As you can see, 1.6 volts is low compared to the 5 volts peak that is typical. But I still think it is sufficient to trigger the CDI based on the CDI designs that I have taken apart.
The 39 volts versus 56 volts AC on the ignition power pin is a bit nebulus since you had a dying battery and the measurements were done on different days. The voltage you measure is also directly proportional to engine cranking speed, and therefore directly related to battery charge. You need to measure both conditions within moments of one another to get any useful conclusions out of them.
#9
05-31-2012, 12:22 AM
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There is no indication one way or the other from these measurments that relate to your coil. Sorry...
.
#10
05-31-2012, 12:32 AM
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So no, a disconnected kill switch will not prevent a quad from starting up. But a disconnected kill switch can keep you from shutting off the quad once it starts. Keep this in mind. How will you shut off the quad if it does start up? Supose the engine runs away at full throttle? There is high voltage on the kill switch wire when the quad is running, so you can't safely do it with your fingers.
One way is to turn on a kill switch (like turn off the ignition switch), and take a pair of insulated pliers, grab the kill switch wire and plug it back into the CDI. Make sure your fingers aren't part of the circuit... Plan this in advance so you know what to do if things go major wrong...