Join Date: Mar 2002
Location: Austin, TX, USA
Re: No spark...
That's a stumper. Your description of your wiring technique sounds about right. Almost sounds like your wiring isn't what you expect. I can't imagine how a volt meter could cause it to run. A cheap volt meter has at least 10,000 ohms input impeadance, which won't allow much useful current to flow - certainly not enough to excite a coil. Almost sounds like your coil is wired backward (so your probing ground on the coil) and your meter is on Amps which completes the ground to the valve cover. Make sure your probes are not in the amperage inputs.
Coil frame must be grounded. The ECM should provide power and ground for the coil primary I believe. The coil may have a diode in it that could cause problems if the polarity was reversed. I'm not sure if the primary should be grounded (internally) to the coil frame or not...I would presume not, but get the facts in a service manual. If the primary was grounded to the coil frame, that might say something more about the grounding issues.
Most sensors and servos on a ECM vehichle have their own power and ground (and signal) lines that are isolated from the engine ground except for a shunt wire from the ECM itself to the vehicle chassis.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI