J. E. Howell Model Engine Plans

Internal Combustion Engines => Ignition, Throttle, Magnetic Pump => Topic started by: ahowell on February 11, 2013, 10:20:33 AM

Title: TIM-6 troubleshooting
Post by: ahowell on February 11, 2013, 10:20:33 AM
Got this e-mail from John on Feb 8th, 2013:


Dear Sir,

I am having problems getting a spark from your TIM-6 with your coil and your Honda spark plug. This is for a v Twin engine that was made from your plans.

The TIM 6 units light up the led when the flywheel is turned and the piston is near TDC. Nothing.

I then tried to test the coils that I first bought from you. I wired the circuit as follows:

Negative 6 v battery to the negative terminal on the coil.
Negative 6v battery to the threads of the Honda spark plug.
White wire with 1k resistor inline from the Spark terminal of the coil to the top of the spark plug.
Red wire from the plus terminal of the 6 v battery to the plus terminal of the coil (intermitently). The plug is brand new and the gap is set to .017" . Nothing happens.

I then bought two more coils from you figuring that I might have damaged them in some way. Same setup as above and no spark.

What am I doing wrong? Everything seemed to follow your diagrams both on the TIM 6 sheets and the diagrams on your "The Model Engine Ignition Spark Coil" sheet.

One other question......when the LED lights can I assume that the circuit to the coil (+6v) is closed?

Thanks for your help. Can't wait to get the engine running.

John F. Garbarino


Hello John,

Sorry to hear you are having issues, as they are pretty rare.  The TIM-6 is a simple and usually reliable ignition system.  Have you checked all the tips from links on our web site and user forum?  Usually the biggest problem is weak or improper grounding.  Yes, when the LED is on, the circuit is closed and the coil is energized.

It's also possible that you have a bad transistor somewhere.  If the LED lights up, then the HALL sensor is working, but one of the two transistors that feed the coil could be bad or improperly soldered.

So, check to make sure all ground connections are solid.  If still nothing, I can send you some replacement transistors, or you can send me your TIM-6 and I can test it here.

Also, make sure your battery can produce a minimum of 5 amps.  You may have the voltage to run the TIM-6 (and LED), but not enough current (amps) to fully charge the coil.  You should be able to test the coil and spark plug independent of the TIM-6 by simply energizing it manually for a split-second.  A spark should jump as you disconnect power to the coil.

Let me know what you find...