ACDelco MR43LTS Marine Resistor Spark Plug | MerCruiser & GM Inboard
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
ACDelco Marine Resistor Spark Plug for MerCruiser & GM Inboard Engines
The ACDelco MR43LTS is a marine-specific resistor spark plug designed for GM-based inboard and sterndrive engines. The built-in resistor suppresses radio frequency interference (RFI) — an important feature on marine engines where electronic interference can affect onboard electronics, GPS, and VHF radios. Sold individually.
Compatible Applications
- MerCruiser GM-based inboard and sterndrive engines requiring ACDelco MR43LTS
- Crusader and Indmar GM V8 marine engines — verify OEM plug number before ordering
Key Features
- Marine-specific resistor design — suppresses RFI to protect onboard electronics
- Copper core center electrode for reliable spark across a wide operating range
- Designed for GM-based marine inboard and sterndrive applications
- Sold individually
Parts Desk Insights
The MR43LTS is the standard copper resistor plug for MerCruiser and GM-based inboard engines — the “MR” prefix designates it as a marine-specific plug, which matters because the resistor is required to prevent ignition noise from interfering with onboard electronics. It’s the right plug for routine tune-ups and spark plug replacements on these engines, and a reliable baseline choice before considering an upgrade to platinum or iridium. Always verify your engine’s OEM plug specification before ordering, as GM marine engines can use different heat ranges. For a longer-life iridium upgrade option for GM marine engines, see the ACDelco 41-993 Iridium Spark Plug or the ACDelco 411104 Iridium Spark Plug.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 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.