Got a problem with my MT57. Four good flights on Sunday, started motor for #5, started OK then stopped and would not restart.

Confirmed no spark at the plug so gave up for the day. Tonight started some diagnostics, took the switches (mechanical + FO) out of the circuit to find that the plug would spark sometimes but not others. It would sometimes spark a number of times in succession then just stop. Battery checked OK and I could not find anything that would make it either work or not work.

I tried to test the Hall sensor by using my multimeter as a current meter. Read 6.4mA nornally increasing to 7.27mA when the magnet was parked near the sensor. Don't know what I should be seeing, but this was consistent and seemed to me to suggest that the sensor was OK.

As of now my conclusion is that there is an intermittant fault in the ignition module. Would welcome any advice as I am fairly new to petrol engines.

Terry

Rcexl ignition troubleshooting.

Take an old expendable servo extension and cut off the male plug end, separate the wires, strip a bit of insulation from each of the 3 leads and plug the other end into the sensor lead on the ignition module. Put a good CM-6 plug in the cap, doesn't need to be all the way seated but far enough for the hex of the plug to make contact with the metal shell of the plug cap, plug a fully charged 4 cell battery directly into the ignition. Test for battery voltage at the red and black wires of the test extension you made and plugged into the sensor lead of the module, if there is no voltage replace the module, if there is battery voltage......Short the white and black wires together, every time you break this connection there should be a spark, no or intermittent spark=bad module, has good spark......Remove the test lead and plug the sensor on the engine into the module and turn the engine over, no spark, replace the sensor, good spark.... Remove the spark plug, look down into the plug cap and turn the engine over, if you see spark arcing through the silicone boot to the metal shell, replace the spark plug cap, no visible spark but you hear a snap.....Put a small screw driver into the bottom of the cap, turn the engine over and you should observe spark jumping from the screw driver to the plug cap shell outside of the silicone boot, an arc of about 1/4"-3/8", if it does this there is nothing wrong with the ignition, if you hear an arc but it's not in the cap with the screw driver it could be a problem with the <font color="#000000">resistor</font> in the cap or the high tension lead where it goes into the cap, replace the plug cap.

All of this can be done on a bench, the plug does not need to be grounded to the engine, and takes less than a tenth of the time to do than it takes to type it out.<span class="info">

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That should be posted as a sticky Jody.
Maybe pasted in the "Gas for newbies" thread.

The most straightforward and direct test sequence I have seen written in one place.

Ahh shucks, thank you Steve.

Bob is welcome to use it in his newbie thread if he wishes, or anyone else may post it where ever they wish except another engine dealers website. 

Thanks Jody, will give it a try

Terry