CDI Electronics 8-Cylinder Spark Gap Tester | Adjustable, Enclosed, Ignition Diagnostic Tool
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
Diagnose Ignition Problems Before You Replace Parts.
The CDI Electronics 8-Cylinder Spark Gap Tester is a professional-grade diagnostic tool for testing spark output on marine and automotive ignition systems. By placing the tester inline between the ignition wire and the spark plug, you can visually confirm whether each cylinder is producing a strong, consistent spark — helping you pinpoint weak or missing ignition before replacing coils, stators, or other components.
The enclosed design helps reduce the risk of igniting fuel vapours during testing, making it a safer choice for use in the marine engine compartment. The adjustable spark gap lets you set the resistance level to match the demands of your ignition system, and the heavy-duty wire allows the tester to be mounted in any position for hands-free use during cranking tests.
Note: Ignition wires are sold separately.
Key Features
- Tests up to 8 cylinders — suitable for inline 4, V6, and V8 engine configurations
- Adjustable spark gap — set resistance to match your ignition system requirements
- Enclosed design — helps reduce the risk of igniting fuel vapours during testing
- Heavy-duty wire — mount in any position for hands-free testing during engine cranking
- Ignition wires sold separately
Compatible Applications
- Marine outboard and sterndrive engines with 4, 6, or 8-cylinder configurations
- Diagnosing weak or missing spark on Mercury, MerCruiser, Yamaha, Volvo Penta, and other marine engines
- Testing ignition coil output before replacing coils or stators
- Automotive ignition systems requiring spark gap testing
- Any application where visual spark confirmation is needed during ignition diagnosis
Parts Desk Insights
This tester is the right tool when you're chasing a no-start, rough idle, or misfire and want to confirm whether the ignition system is delivering spark before spending money on parts. It's especially useful for isolating which cylinder is losing spark on a multi-cylinder engine — something that's difficult to determine without a dedicated tester.
Use this tool to test before replacing ignition components. If the tester confirms weak or no spark, the next step is typically checking the ignition coils — see the Mercury OEM Ignition Coil 806673T1 or the Mercury MerCruiser Ignition Coil Kit 8M0079202. If coils test good but spark is still weak, the stator may be the cause — see the CDI Electronics Mercury Stator. For spark plugs, see the Quicksilver NGK Iridium Spark Plug Set.
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
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.