Manifold Heater Question

[zak]

My truck's manifold heater wasn't working so I chased it down to no spark. I bench tested the coil and could only hear some internal buzzing, but no spark. Where can I get another coil?

 

[cranetruck]

Hearing the "buzzer", actually a relay, is half the battle...how do you have the spark plug connected, have you checked all contact points? The cable and connectors to the spark plug provide the ground, no other external ground needed...here I go talking about grounding again....
Spark gap should be 1/10 of an inch.
Test the whole system like this.

 

[zak]

The plug wire checked ok with ohm meter. I had the unit in a vise, with the plug wire minus plug about an 1/8 off the vise. I supplied power directly to the positive pin and negative to the case. I assumed that the case is grounded. When it was in the truck, it would not spark with plug grounded on the head.

 

[cranetruck]

The case is grounded.
PM sent.