Poulan 245A Ignition Coil (Wiring Diagram & Test)
The Poulan 245A uses a magneto ignition: flywheel magnets induce voltage in the coil, which sends it through the plug lead to the spark plug. A grounded kill wire stops ignition. Before buying a coil, isolate that wire, verify spark, inspect the plug and coil gap, and confirm the installed ignition parts and service specifications for your saw’s serial number.
If the starter cord has been pulled again and again with no start, a failed coil may seem like the obvious answer. But a pinched kill wire, damaged plug, poor coil ground, or incorrect air gap can produce the same no-spark symptom. Testing in order helps you find the cause without spending money on a part that may be fine.
Poulan 245A coil identification, wiring, and safety preparation
The ignition coil sits beside the flywheel and has a high-tension lead to the spark plug and a small kill-wire connection. The coil’s metal core mounts to the engine. Parts and specifications can vary, so identify the installed ignition system before ordering a replacement or setting its gap.
The flywheel magnets pass the coil as the engine turns. This creates the voltage needed at the spark plug. The stop switch works by grounding the coil’s kill terminal: in RUN, that circuit is open; in STOP, the switch connects it to ground.
Coil high-tension lead ───────── Spark plug
Coil kill terminal ───────────── Stop-switch lead
|
RUN: open circuit
STOP: connect to ground
Coil core / mounting feet ────── Engine ground
The drawing shows the basic circuit, not the exact routing of every wire on every saw. Check the wiring against the parts and service information for your serial number. The kill wire must not touch the coil core, engine, or flywheel except through the stop switch when STOP is selected.
Prepare the saw before testing
A safe test keeps hands clear of the chain and prevents an accidental start. Work outdoors with the engine cool, place the saw on a stable surface, and keep fuel vapors and other flammable material away from any spark test. Remove the plug cap before handling the coil or flywheel.
For cranking tests, secure the saw and use an approved inline spark tester. Do not hold a plug lead or spark plug by hand while pulling the starter. Keep the chain clear of people and objects, and follow the saw’s starting instructions.
Before buying a coil, note its markings, mounting shape, wire connections, and the flywheel it works with. Bar length, chain pitch, fuel mix, and carburetor settings do not establish ignition-coil fit. Match the part to the ignition type, flywheel, mounting pattern, and parts identification.
Field operation: spark verification and controlled restart
A spark test answers whether the ignition is producing a visible spark, but it does not by itself prove the coil is bad or good under all conditions. Test first with the kill circuit connected, then isolate it if needed. Keep the disconnected wire insulated and restore it before operating the saw.
Start with a known-good, correctly specified spark plug if one is available. Check for cracks, heavy deposits, a damaged electrode, or a loose plug cap. A faulty plug or cap can imitate a coil fault, so replace or test them before condemning the coil.
- Set the stop switch to RUN and connect an approved inline tester as its instructions direct.
- Secure the saw, keep clear of the chain, and pull the starter as directed by the saw manual.
- If the tester shows no spark, switch off and remove the plug cap before inspection.
- Disconnect the small kill wire at the coil. Keep its end insulated from the engine and metal parts.
- Repeat the spark test. Do not leave the kill wire disconnected after testing.
| Test result | What it points to | Next check |
|---|---|---|
| Spark with kill wire connected | Ignition can produce spark during this test | If the saw still will not start, the coil may not be the cause |
| No spark connected, spark after wire is isolated | Kill circuit is grounding ignition in RUN | Inspect the wire, switch, and routing for a short |
| No spark with kill wire isolated | Fault may be at plug, cap, coil, ground, flywheel, or gap | Continue checks before replacing parts |
| Spark appears or disappears when wiring moves | Possible damaged insulation or loose connection | Inspect the full wire route and connectors |
If spark returns with the kill wire disconnected, the coil was able to spark during that test. Look for a pinched, abraded, or trapped kill wire, or a stop switch that remains grounded in RUN. Repair the fault, then reconnect the wire and verify both RUN and STOP. A disconnected kill wire removes the normal shutdown control, so never operate the saw that way.
If there is still no spark, test with a known-good, correctly specified plug and tester. Inspect the plug cap and high-tension lead for damage. Check that the coil mounting feet and core make clean, secure contact with the engine, and look for damaged wiring or flywheel contact.
Ignition maintenance, coil clearance, and electrical testing
Coil clearance, also called the air gap, is the space between the coil laminations and the flywheel. It must match the specification for the exact coil and flywheel combination. Do not use a generic gap, resistance value, or fastener torque in place of the applicable Poulan service information.
Check coil resistance against the correct specification
Resistance is the opposition to electrical flow, measured in ohms. With the coil isolated from the stop-switch wire, a meter can check the primary circuit from the coil’s low-voltage or kill terminal to its core, and the secondary circuit from the plug lead to the core.
First identify the coil and find its test method and resistance range in the applicable service information. There is no safe universal resistance value for every coil used on a 245A. A reading within specification does not prove that the coil will work under compression, and a reading outside specification is meaningful only if the meter setup and test points match the service instructions.
| Check | Setup | What it can show | Important limit |
|---|---|---|---|
| Primary resistance | Kill terminal to coil core; kill wire disconnected | Open or out-of-range primary circuit | Use the specification for the identified coil |
| Secondary resistance | Plug lead to coil core | Open or out-of-range secondary circuit | Plug cap design can affect the reading |
| Coil ground | Inspect mounting feet and contact surfaces | Loose or poor contact to engine | Clean and secure; follow service instructions |
| Spark test | Approved inline tester during cranking | Whether spark is present during the test | Does not guarantee spark under every running condition |
If the resistance reading is unclear, confirm meter contact and the specified test points before drawing a conclusion. Do not replace a coil based only on a generic online resistance figure.
Set clearance and install a matched replacement
Inspect the flywheel and coil laminations for rubbing, damage, loose fasteners, or debris. Turn the flywheel by hand through a full rotation and confirm it does not contact the coil. If it does, stop and correct the alignment before cranking.
When service information confirms the coil and flywheel combination, set the air gap to that specified value using the prescribed gauge or method. Do not rely on a business card or an assumed common gap unless the applicable service procedure calls for it. Tighten the fasteners to the specified torque; do not guess.
A replacement coil must match the ignition system, flywheel, mounting pattern, and parts identification. Do not force a coil into place or use a part simply because its plug lead looks similar. After installation, connect the kill wire, test spark, and verify that STOP prevents ignition and RUN allows it.
Diagnostic examples: what the test result changes
These are examples of how to read test results, not claims about a particular saw. In one common pattern, the tester shows no spark with the kill wire connected, then shows spark after that wire is isolated. That result shifts attention to the stop switch and wire routing rather than the coil.
In another pattern, there is no spark even with the kill wire isolated. That does not prove the coil has failed. I would next check the plug and tester, coil ground, flywheel condition, air gap, and coil resistance against the correct specification. Replace the coil only after these checks point to it.
Storage and seasonal care: protect the ignition system
Storage does not require a special coil adjustment, but damaged wiring and corrosion can turn a working ignition into a no-spark fault. Before returning the saw to use, inspect the kill wire, plug cap, coil mounting, and visible flywheel area. Keep the kill circuit connected and confirm normal shutdown.
Avoid pulling or trapping the kill wire when removing covers or servicing the saw. If the saw is stored or moved with a loose cover, check that no wire has been pinched against the engine or coil. After any ignition work, test that RUN permits starting and STOP shuts the engine down before cutting.
The key point is simple: isolate the kill circuit, verify the spark path, then check the coil and its clearance against the correct service data. That sequence helps distinguish a wiring fault from a failed coil without guessing at parts.
Frequently asked questions
Where does the kill wire connect on a Poulan 245A coil?
It connects to the coil’s small low-voltage kill terminal and runs to the stop switch. In STOP, the switch grounds that terminal; in RUN, the circuit should be open.
Can a bad stop switch cause no spark?
Yes. A switch or kill wire that stays grounded in RUN can prevent ignition. If spark returns when the kill wire is isolated, inspect the switch and wire before replacing the coil.
Is it safe to run the saw with the kill wire disconnected?
No. Disconnecting the wire can help isolate a fault during a controlled test, but it removes the normal shutdown function. Reconnect and verify the stop switch before operating the saw.
What air gap should I use for the coil?
Use the specification for the exact coil and flywheel combination identified on your saw. Do not assume a generic gap is correct; 245A parts or production revisions may differ.
What resistance should a Poulan 245A ignition coil read?
There is no universal value that applies to every 245A coil. Identify the installed coil and use its applicable service specification and test method.
Does a normal resistance reading prove the coil is good?
No. Resistance checks can find some open or out-of-range circuits, but an acceptable reading does not prove the coil will produce spark under compression.
Should I replace the coil if there is no spark?
Not yet. First check the plug, tester, kill circuit, wiring, coil ground, flywheel, and air gap. Replace the coil only when testing supports that diagnosis.
How do I confirm a replacement coil fits?
Match it to the ignition type, flywheel, mounting pattern, and parts identification. Bar length, chain pitch, and carburetor settings do not confirm coil compatibility.
How do I know the repair is complete?
With the kill wire reconnected, confirm that RUN permits spark and starting, and that STOP shuts the engine down. Check the coil does not touch the flywheel through a full rotation.
(This article was written by one of our staff writers, Robert Callahan. Visit our Meet the Team page.)
