Mercury MerCruiser Quicksilver Delco HEI Ignition Coil 806673T1
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Mercury MerCruiser Quicksilver Delco HEI Ignition Coil 806673T1
Part Number: 806673T1
Brand: Mercury / Quicksilver
Product Type: Ignition Coil (OEM)
System: Delco HEI Distributor Ignition
Application: GM V8 MerCruiser EFI / TBI inboard & sterndrive engines
Supersedes: 806673T, 806673
GTIN / UPC: 745061284067
Quantity Required: 1 per engine
Weight: 0.45 kg
What This Part Does
The 806673T1 is a genuine OEM high-voltage ignition coil for selected MerCruiser GM V8 gasoline engines equipped with Delco HEI distributor ignition. It works within the distributor and ignition assembly — alongside the distributor module, ignition harness, distributor cap, and spark-plug wires — to deliver the high-voltage spark required to fire the engine at all RPM ranges. This is a MerCruiser inboard and sterndrive coil, not a Mercury outboard coil.
Compatible Applications
Confirm fitment by engine model, serial number, and ignition system type before ordering. 806673T1 is documented for GM V8 MerCruiser engines using Delco HEI ignition — it does not apply to Mercury outboard engines.
- MerCruiser 350 MAG EFI Ski (TBI) 5.7L GM 350 V8 — serial 0F215561–0F820706
- MerCruiser 350 MAG Alpha EFI Gen+ — serial 0F800300–0K001508 and selected 0K-series
- MerCruiser 5.0L EFI GM 305 V8 — serial 0L012052–0L339999
- MerCruiser 5.7L Alpha EFI (TBI) — serial 0F355305–0F752389
- MerCruiser 5.7L Bravo EFI (TBI) — serial 0F225560–0F752399
- MerCruiser 5.7L EFI — serial 0F752400–0K999999 and selected 0L-series
- MerCruiser 5.7L EFI 2-BBL TBI
- MerCruiser 5.7LX EFI 4-BBL TBI
- MerCruiser 5.7LX Bravo EFI Gen+
- MerCruiser 5.7L EFI Gen+ Repower Plus
Serial Number Notice
806673T1 should be matched to the engine model, serial number, and confirmed Delco HEI ignition system before ordering. Do not assume fitment based on the Mercury Marine part number prefix alone — this coil is specific to MerCruiser GM V8 inboard and sterndrive applications, not Mercury outboards.
When to Replace
- Weak or intermittent spark on diagnosis
- No-start condition caused by loss of coil output
- Misfire under load, especially when the engine is at operating temperature
- Internal coil breakdown when hot (coil tests good cold, fails warm)
- Burned or corroded primary terminals
- Cracked or damaged coil housing
- Failed resistance or output tests per the MerCruiser service manual
Diagnose the ignition system before replacing the coil — the distributor module, wiring harness, ignition sensor, and secondary ignition components can produce similar symptoms.
Installation Notes
- Disconnect battery power before servicing the ignition system
- Inspect the coil electrical terminals, coil-to-distributor lead, and ignition harness 817376T01 during replacement
- Inspect distributor cap, rotor, and spark-plug wires while the ignition assembly is accessible
- Compare the removed coil terminals against the replacement before installation
- Test for spark output and check for fault codes after reinstating battery power
Part Number Cross-Reference
- Current OEM: 806673T1
- Supersedes: 806673T
- Supersedes: 806673
- Supersession chain: 806673 → 806673T → 806673T1
- Aftermarket cross-reference: Sierra 18-5442 (third-party reference only)
Technical FAQ
Q: Is 806673T1 a Mercury outboard coil?
A: No. Parts Desk documentation confirms this is a MerCruiser inboard and sterndrive coil for GM V8 engines with Delco HEI distributor ignition. If you have a Mercury outboard, confirm your engine model and serial number and look up the correct ignition coil for your specific outboard application.
Q: What is the Delco HEI system?
A: Delco HEI (High Energy Ignition) is a GM-designed distributor-based ignition system used in selected MerCruiser engines. The ignition coil mounts inside or adjacent to the distributor and works with the distributor module, cap, rotor, and spark-plug wires to deliver timed ignition voltage to each cylinder.
Q: What symptoms indicate a failing ignition coil?
A: Common symptoms include intermittent misfires (especially under load or when warm), hard starting, rough idle, hesitation on acceleration, and power loss. These symptoms can also be caused by a failing distributor module, worn spark plugs, or damaged plug wires — diagnose before replacing the coil.
Q: What does the T1 suffix mean in 806673T1?
A: It indicates a revision in the Mercury OEM part numbering. 806673T1 is the current active OEM number, superseding the earlier 806673T and the original 806673. Always use the current number when ordering.
Parts Desk Insights
Best use case: Order 806673T1 after confirming the Delco HEI coil is the diagnosed failure point on a MerCruiser 5.0L, 5.7L, or 350 MAG EFI/TBI engine. It is most commonly replaced during ignition troubleshooting when the engine misfires or fails to start and the distributor module and sensor have already been cleared as causes.
Common issues: The most frequent mistake is ordering this coil for a Mercury outboard — 806673T1 is a MerCruiser inboard coil only. Always confirm the engine is a GM V8 MerCruiser with Delco HEI ignition before ordering. A second common issue is replacing the coil without inspecting the distributor module and ignition sensor — these components share the same ignition circuit and can produce identical symptoms when failing.
Related Parts
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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