The classic call

An older Evinrude or Johnson two-stroke cranks strong but never fires. Before condemning the powerpack (the expensive guess), work the chain in order — most no-spark calls on these engines are a kill circuit or a connection, not the pack.

Test setup

Use an adjustable spark gap tester — a plug lying on the block is not a valid test. A healthy magneto/CDI system should jump a substantial open-air gap; check the service manual for the expected gap and any peak-voltage (DVA) values for your model.

Diagnosis order

1. All cylinders or some?

• No spark on all cylinders → shared component: kill circuit, stator, powerpack, key switch, lanyard switch.
• No spark on one cylinder → that coil, its wiring, or one powerpack output.

1. Rule out the kill circuit first. Disconnect the kill wire (commonly the black/yellow on OMC — verify on the wiring diagram) at the powerpack and retest. Spark returns? The problem is the key switch, lanyard, harness chafe, or a pinched wire under the flywheel — not the ignition components. This one step solves a huge share of calls.
2. Check the basics: clean, tight ground between powerpack, coils, and block; connectors green with corrosion get cleaned before any parts are ordered.
3. Stator and timer base/trigger: resistance and DVA-test per the service manual values. Look under the flywheel for a melted or leaking stator — visible tar means it's done. Inspect the flywheel magnets for cracks and debris.
4. Coils: cracked bodies on old OMC coils are common; test resistance per manual and replace as pairs where recommended.
5. Powerpack last, by elimination or substitution — it is the least testable and most expensive guess.

Common mistakes

• Replacing the powerpack first on a bad kill wire
• Testing spark with a plug on the block and calling weak spark "good"
• Ignoring a low-reading battery/dirty connections on models where cranking speed affects spark
• Pulling the flywheel without the proper puller (never pry or hammer the flywheel edge)

When to walk away

If the flywheel is seized to a rusty crank taper, or the wiring harness is crumbling insulation end-to-end, quote a harness/ignition refresh honestly — chasing one wire at a time dockside will burn the customer's money.

Safety: CDI systems bite hard — use insulated tools, and remove plugs/ground the leads when cranking for tests. Fuel-rich cylinders can fire vapor out the plug holes.