All Ignitions have grounds.
If you don't have a seperate wire, then you have a cap that supplies the ground.
If the cap is not electrically tight, then this could be your problem.
You may want to put a hose clamp on it to secure the ground electrically.

It has a hose clamp on each cap and they are very tight. There are three wires to the sensor and two to the battery.

From what you have described the ign module is fine, there must be a wire loose at the connection to the sensor. That or you have really have bad luck with the sensor unit it self. Mine worked fine for 3 flights today, guess I didn't jinx my self One last thought is that there may be a ground coming loose in the module itself???

I don't think there is a problem with the module because it does sent a single spark when the switch is turned on. Per the diagnostic test on the CH site I believe that means the module is ok. I had the same problem before and a new hall sensor chip fixed it right up.

Maybe intermittent lose of ground killing the sensor???

RTK, I think you are exactly right. I am going to call CH in the morning and see if I can get one of the new sensors that has the extra ground wire.

They should not go out that frequently

Maybe tkg will chime in and enlighten us.

I called CH today and told them about the problem. They told me that BME uses a substandard wire on their Hall Sensors. Bme uses a six strand wire and CH uses a twelve strand wire which is supposed to be more vibration resistant. The CH sensors also have an additional ground wire that attaches to the bolt that holds the hall sensor mount. I have a feeling this will cure the problem but I ordered three just in case.

I have purchased wires from both companies.
C&H does have the 4 wire type and the wire guage and strand count seems to be the same. The difference I have found is that C&H doesn't have the bracket and you have to reuse the one on the engine. BME will supply the bracket or at least they did on the one that I got. All my sensor failures came from broken ignition ground wires. When the ground breaks on both sides, it will fry the sensor.

I peeled all the insulation off at both ends and the wire and solder joints are in very good shape. Since this is my second failure I have two brackets to use.