Ask the Editors: Mysteriously Missing Spark
Let the diagnostics begin!
I tried the pull and electric start and nothing happened. I pulled the spark plug and found it wasn’t making spark when I pull cranked it but would spark well (but just once) after I’d let the electric start button go.
I replaced the spark plug and the ignition coil and it still does the same thing. I’m thinking maybe a ground problem somewhere?
That’s a very unique situation and while we have no simple explanation for what would cause your machine to make spark once only after you’ve released the electric starter, your best bet when dealing with electrical is to start your diagnostics at the most basic and then expand your trials until you shake down the issue.
You were wise to begin by replacing the plug and coil but since the condition still persists, go a little further and check things like the spark plug wire, the cap, etc.
Next pop the seat and check the main fuse. Sometimes a fuse doesn’t blow completely but fails partially and still makes some degree of contact.
If all of these things look good, there is a strong possibility the fault could be with the ignition switch itself. Most modern ATVs are equipped with various safety settings as well- usually a neutral safety kill switch to keep an ATV from being started in gear. Grab an electrical multimeter and begin the process of checking these switches (including the primary ignition switch itself) by setting the meter to Ohms and placing one lead on the positive of the switch and the other to ground. You’ll want a continuity reading of zero.
Next take a look at the machine’s solenoid. Grab your voltmeter and connect the red lead to the solenoid wire coil (you should see where the positive lead of the battery connects to the solenoid) while keeping the black lead on the negative terminal of your quad’s battery. Once you’ve completed this circuit, you should get a reading of 12 volts. If you get no reading or a number wildly different, it is indeed time to pick up a new solenoid.
If all of this checks out, we would then move on to confirming the resistance of the stator. Again perform a continuity from the terminal tabs of the connector. With your meter still set to Ohms place the leads onto tabs A to B, B to C and then A to C. The multimeter should read under 1 Ohm for all three tests. Anything higher and there’s your problem.
Now check to make sure the stator isn’t grounding. Place your red lead to the stator’s connector and the black lead to the negative terminal of the battery. You want zero Ohms here as well.
While you’ve got access to your stator, time to check the voltage regulator. To do this set your meter to Diode function and place your red lead on the positive wire (red) and then touch the negative lead to each of the stator inputs. You should get no readings if all is well. Now do the reverse: Connect the negative lead to the positive diode and touch the positive lead to each of the stator inputs. Now you should get readings (though the actual numbers aren’t important).
If everything checks out up until this point, we’d turn our attention to the machine’s CDI box. These can’t really be tested with a meter so if you made it this far with nothing else manifesting, it may be worth buying a replacement box and plugging it in on account of process of elimination diagnostics alone.
