Ask the Editors: My Spark is Weak
It is possible – but there is an issue you should consider even before tearing into coil diagnostics. We’d go as far as to say 80% of all situations like this are caused by improper grounding. This is especially true for older machines.
After ruling out all of the areas you have already replaced/ repaired, there are a few culprits that remain: High resistance in the coil, high resistance in the plug lead, improper gap at the pulse generator, failing ignition module, bad ground on coil, even something as simple as improper plug gap.
Assuming after cleaning up the flywheel and stator, you then got out a multimeter and checked the components’ output (the stator is a common cause for weak or intermittent spark), we would begin by inspecting the ground on the coil.
If this checks out, grab a service manual to be sure of all the ground wires- then begin the process of testing each with a meter. We’re almost positive this is where you’ll find the problem.
