need some help chinese 250 no spark
#1
10-19-2011 | 05:03 PM
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need some help chinese 250 no spark
hi im new here and signed up cause this site has helped me alot i have a chinese 250 that only sparks once the kill switch, coil and plug are good the a/c ignition power wire puts out 50v a/c and the ignition trigger wire puts out 1volt just at the start of crankin than nothin while cranking any advice
#2
10-19-2011 | 10:59 PM
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1 volt on the trigger wire sounds really high, and then no voltage after that is wrong too. You should be seeing 0.3 volts AC or so. What I wondering is whether the voltage you see on the trigger wire is coupled over to an open trigger connection via the stray capacitance of the wiring.
Look at the following procedure and use it to measure the resistance of the trigger winding to ground (that would be step #3):
Is that a picture of your CDI?
What do you measure for the trigger wire resistance? If there are two grounds on your CDI connector be sure to measure from the trigger pin to each ground and report both.
Do you know what brand your 250cc quad is? I'm asking only to see if I happen to have a wiring diagram specific for your quad. Else we will just have to wing it...
It wouldn't hurt to go through the entire procedure and report back what you find for each of the steps. I might see something else in the results that looks incorrect.
Look at the following procedure and use it to measure the resistance of the trigger winding to ground (that would be step #3):
To troubleshoot no spark problems on a 6 pin AC powered CDI it makes sense to start in the middle (the CDI), measure as much as we can and branch out from there. For the CDI to do its thing it needs power, a trigger pulse, and it must must be inhibited via the kill switch input pin.
1) Unplug the CDI. Turn the ignition switch on. Set all kill switches the the "run" position. In the wiring harness, measure the resistance of the kill switch pin to the ground pin on the 20K ohm scale. It should read infinite ohms (same as when the meter leads are hanging free and not touching anything). It should not read zero ohms (shorted).
2) Leave the CDI unplugged. Use a meter to measure the resistance of the AC ignition power pin in the wiring harness to the ground wire on the 2K ohm scale. You should read approximately 400 ohms. What do you measure?
3) In a similar fashion measure the resistance of the Ignition Trigger Pulse pin to the ground pin. You should see 150 ohms or so. What do you measure?
4) Switch your meter over to measure AC volts on the 200 volt scale. Leave the CDI unplugged. While cranking the engine, measure the voltage on the AC Ignition Power pin in the wiring harness to the ground pin. You should measure 40 to 80 volts AC. What do you measure?
5) Set your meter down to the lowest scale you have for measuring AC volts. 2 volts would be ideal, but some meters don't go that low. In that case use the lowest scale you have. While cranking the engine, measure the voltage on the Ignition Trigger Pulse pin in the wiring harness to the ground pin. You should measure 0.2 to 0.5 volts AC. What do you measure?
6) Now plug the CDI back in. Measure the AC voltage on the Ignition Coil pin to the ground pin using the 200 volt scale. If you have to, use a sewing pin to poke through the wire insulation and then put the meter probe on the sewing pin. But don't hold your fingers on the connection during the next test - there may be high voltage here when the engine is turning. With the ignition on and all kill switches set to the "run" position, crank the starter motor. You should see voltages bouncing around at random values and the meter captures all or part of a spark event. What do you see?
1) Unplug the CDI. Turn the ignition switch on. Set all kill switches the the "run" position. In the wiring harness, measure the resistance of the kill switch pin to the ground pin on the 20K ohm scale. It should read infinite ohms (same as when the meter leads are hanging free and not touching anything). It should not read zero ohms (shorted).
2) Leave the CDI unplugged. Use a meter to measure the resistance of the AC ignition power pin in the wiring harness to the ground wire on the 2K ohm scale. You should read approximately 400 ohms. What do you measure?
3) In a similar fashion measure the resistance of the Ignition Trigger Pulse pin to the ground pin. You should see 150 ohms or so. What do you measure?
4) Switch your meter over to measure AC volts on the 200 volt scale. Leave the CDI unplugged. While cranking the engine, measure the voltage on the AC Ignition Power pin in the wiring harness to the ground pin. You should measure 40 to 80 volts AC. What do you measure?
5) Set your meter down to the lowest scale you have for measuring AC volts. 2 volts would be ideal, but some meters don't go that low. In that case use the lowest scale you have. While cranking the engine, measure the voltage on the Ignition Trigger Pulse pin in the wiring harness to the ground pin. You should measure 0.2 to 0.5 volts AC. What do you measure?
6) Now plug the CDI back in. Measure the AC voltage on the Ignition Coil pin to the ground pin using the 200 volt scale. If you have to, use a sewing pin to poke through the wire insulation and then put the meter probe on the sewing pin. But don't hold your fingers on the connection during the next test - there may be high voltage here when the engine is turning. With the ignition on and all kill switches set to the "run" position, crank the starter motor. You should see voltages bouncing around at random values and the meter captures all or part of a spark event. What do you see?
What do you measure for the trigger wire resistance? If there are two grounds on your CDI connector be sure to measure from the trigger pin to each ground and report both.
Do you know what brand your 250cc quad is? I'm asking only to see if I happen to have a wiring diagram specific for your quad. Else we will just have to wing it...
It wouldn't hurt to go through the entire procedure and report back what you find for each of the steps. I might see something else in the results that looks incorrect.
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