Engine & Drive Parts
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NGK Spark Plugs 5599 Spark Plug 5599 ITR4A15 (Mercury 8M0204739 8m2018369)
NGK Spark Plugs
$22.49 $11.99NGK Spark Plugs 5599 Spark Plug 5599 Same as Mercury 8m2018369 Original equipment on many late model applications Iridium at the fine-wire center electrode and platinum at the ground electrode provides maximum durability and...- Part Number:
- 41-ITR4A15
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 5599
- What's in the Box:
- (1) Spark Plug
$22.49 $11.99 -
AC Delco Spark Plugs Spark Plug AC#Mr43T Resistor Mr43T
AC Delco Spark Plugs
$7.04 $4.99AC Delco Spark Plugs Spark Plug AC#Mr43T Resistor Mr43T ⚠️ Price is for one spark plug- Part Number:
- 603-MR43T4
- Availability:
- In Stock - Ships same or next business day.
- OEM #:
- Mercury 33-898264001
- What's in the Box:
- (1) Spark Plug
$7.04 $4.99 -
NGK Spark Plugs 3623 Spark Plug BPR6EFS
NGK Spark Plugs
$7.99 $4.54NGK Spark Plugs 3623 Spark Plug 3623 BPR6EFS Chosen by more automotive, and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. •?Triple...- Part Number:
- 41-3623
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 3623
- Pack:
- 1
- Pkg.:
- Boxed
- What's in the Box:
- (1) Spark Plug
$7.99 $4.54 -
NGK Spark Plugs 3521 Spark Plug Cr9Eix 3521
NGK Spark Plugs
$20.39 $10.99NGK Spark Plugs 3521 Spark Plug Cr9Eix 3521 Designed specifically for the performance enthusiast. Iridium IX offers extreme ignitability, improved throttle response and superior anti-fouling. Fine-tipped iridium-center electrode ensures high...- Part Number:
- 41-CR9EIX
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 3521
- What's in the Box:
- (1) Spark Plug
$20.39 $10.99 -
AC Delco Spark Plugs Spark Plug AC#41-983 Double Plated 8M0129146 41983
AC Delco Spark Plugs
$24.49 $13.01AC Delco Spark Plugs Spark Plug AC#41-983 Double Plated 41983 Dual platinum tip provides improved resistance to spark erosion while the platinum center electrode and pad lower the ignition demand voltage. A corrosion resistant shell makes it an...- Part Number:
- 603-41983
- Availability:
- In Stock - Ships same or next business day.
- OEM #:
- Mercury 33-863622001
- What's in the Box:
- (1) Spark Plug
$24.49 $13.01 -
AC Delco Spark Plugs Spark Plug AC#Mr43Lts Resistor 8 Mr43Ltx4 862029
AC Delco Spark Plugs
$7.79 $4.99AC Delco Spark Plugs Spark Plug AC#Mr43Lts Resistor 8 Mr43Ltx 862029 ⚠️ Price is for one spark plug- Part Number:
- 603-MR43LTS4
- Availability:
- In Stock - Ships same or next business day.
- OEM #:
- Mercury 33-86209
- What's in the Box:
- (1) Spark Plug
$7.79 $4.99 -
NGK Spark Plugs 7558 Spark Plug ZFR5F Mercury 8m0204728
NGK Spark Plugs
$8.09 $4.99NGK Spark Plugs 7558 Spark Plug V-Power 7558 Chosen by more automotive, and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. •?Triple gasket...- Part Number:
- 41-ZFR5F
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 7558
- What's in the Box:
- (1) Spark Plug
$8.09 $4.99 -
Sold Out, please call for ETA.
NGK Spark Plugs 4323 Spark Plug 4323
NGK Spark Plugs
$5.89 $4.13NGK Spark Plugs 4323 Spark Plug 4323 Chosen by more automotive, and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. •?Triple gasket sealing...- Part Number:
- 41-BR6FS
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 4323
- Pack:
- 1
- Pkg.:
- Boxed
- What's in the Box:
- (1) Spark Plug
$5.89 $4.13 -
NGK Spark Plugs 4339 Spark Plug 4339
NGK Spark Plugs
$5.99 $4.04NGK Spark Plugs 4339 Spark Plug 4339 Chosen by more automotive, and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. •?Triple gasket sealing...- Part Number:
- 41-DCPR8E
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 4339
- Pack:
- 10
- Pkg.:
- Boxed
- What's in the Box:
- (1) Spark Plug
$5.99 $4.04 -
NGK Spark Plugs 4212 Spark Plug 4212 (Mercury 889246q39)
NGK Spark Plugs
$29.29 $14.74NGK Spark Plugs 4212 Spark Plug 4212 Original equipment on many late model applications Iridium at the fine-wire center electrode and platinum at the ground electrode provides maximum durability and performance The platinum at the ground...- Part Number:
- 41-ILFR6GE
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 4212
- What's in the Box:
- (1) Spark Plug
$29.29 $14.74 -
NGK Spark Plugs Br8Es Solid Spark Plug 3961
NGK Spark Plugs
$5.89 $4.06NGK Spark Plugs Br8Es Solid Spark Plug 3961 Chosen by more automotive, and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. •?Triple gasket...- Part Number:
- 41-3961
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- BR8ES Solid
- Pack:
- 4
- Pkg.:
- Boxed
- What's in the Box:
- (1) Spark Plug
$5.89 $4.06 -
NGK Spark Plugs Bpr9Es Spark Plug 7788
NGK Spark Plugs
$5.89 $4.13NGK Spark Plugs Bpr9Es Spark Plug 7788 Chosen by more automotive, and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. •?Triple gasket sealing...- Part Number:
- 41-BPR9ES
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 7788
- Pack:
- 4
- Pkg.:
- Boxed
- What's in the Box:
- (1) Spark Plug
$5.89 $4.13 -
NGK Spark Plugs 2359 Spark Plug 2359
NGK Spark Plugs
$19.19 $10.99NGK Spark Plugs 2359 Spark Plug 2359 Chosen by more automotive, and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. •?Triple gasket sealing...- Part Number:
- 41-BPR5EFS13
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 2359
- What's in the Box:
- (1) Spark Plug
$19.19 $10.99 -
NGK Spark Plugs 3249 Spark Plug 3249
NGK Spark Plugs
$12.09 $6.73NGK Spark Plugs 3249 Spark Plug 3249 Racing plugs feature a center electrode with a V-groove and a thicker ceramic shell for the high-heat applications in racing engines. Special center electrode designs and configurations to ensure...- Part Number:
- 41-R56738
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 3249
- Pack:
- 4
- What's in the Box:
- (1) Spark Plug
$12.09 $6.73 -
NGK Spark Plugs 4462 Spark Plug Irdium 4462
NGK Spark Plugs
$29.29 $14.74NGK Spark Plugs 4462 Spark Plug Irdium 4462 Original equipment on many late model applications Iridium at the fine-wire center electrode and platinum at the ground electrode provides maximum durability and performance The platinum at the...- Part Number:
- 41-IZFR6J
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 4462
- What's in the Box:
- (1) Spark Plug
$29.29 $14.74 -
NGK Spark Plugs 6431 Spark Plug 6431
NGK Spark Plugs
$7.89 $4.65NGK Spark Plugs 6431 Spark Plug 6431 Chosen by more automotive, and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. •?Triple gasket sealing...- Part Number:
- 41-BU8H
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 6431
- Pkg.:
- Boxed
- What's in the Box:
- (1) Spark Plug
$7.89 $4.65 -
NGK Spark Plugs 2318 Spark Plug Iridium 2318
NGK Spark Plugs
$20.39 $11.99NGK Spark Plugs 2318 Spark Plug Iridium 2318 Designed specifically for the performance enthusiast. Iridium IX offers extreme ignitability, improved throttle response and superior anti-fouling. Fine-tipped iridium-center electrode ensures high...- Part Number:
- 41-BR6FIX
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 2318
- What's in the Box:
- (1) Spark Plug
$20.39 $11.99 -
NGK Spark Plugs 7164 Spark Plug Iridium 7164
NGK Spark Plugs
$17.29 $9.36NGK Spark Plugs 7164 Spark Plug Iridium 7164 Designed specifically for the performance enthusiast. Iridium IX offers extreme ignitability, improved throttle response and superior anti-fouling. Fine-tipped iridium-center electrode ensures high...- Part Number:
- 41-TR55IX
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 7164
- What's in the Box:
- (1) Spark Plug
$17.29 $9.36 -
NGK Spark Plugs Br10Es Spark Plug 4832
NGK Spark Plugs
$5.89 $4.13NGK Spark Plugs Br10Es Spark Plug 4832 Chosen by more automotive, and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. • Triple gasket sealing...- Part Number:
- 41-BR10ES
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 4832
- Pkg.:
- Boxed
- What's in the Box:
- (1) Spark Plug
$5.89 $4.13 -
NGK Spark Plugs 7862 Spark Plug 7862
NGK Spark Plugs
$20.19 $10.75NGK Spark Plugs 7862 Spark Plug 7862 Original equipment on many late model applications Platinum at the fine-wire center electrode as well as at the ground electrode provides extended service life The platinum at the ground electrode adds...- Part Number:
- 41-PZTR5A15
- Availability:
- In Stock - Ships same or next business day.
- Model #:
- 7862
- What's in the Box:
- (1) Spark Plug
$20.19 $10.75
Spark Plugs for Power Boats
Keep your engine performing at its best with high-quality boat spark plugs designed for outboards, inboards, and sterndrives. At PowerBoatSupply.com, we carry a full selection of NGK spark plugs, AC Delco spark plugs, and other trusted marine brands to fit a wide variety of engines. Whether you’re replacing a single spark plug for a boat motor or outfitting an entire set, you’ll find durable, OEM-recommended options that deliver reliable ignition, smooth starts, and long-lasting performance on the water.
Why Spark Plugs Matter for Marine Engines
Spark plugs are a small but critical part of your boat’s ignition system. They provide the spark that ignites the fuel-air mixture, powering your engine forward. Worn or fouled boat motor spark plugs can lead to misfires, poor fuel economy, hard starts, or even engine damage. That’s why routine replacement with the right spark plug type is essential for keeping your boat running smoothly all season long.
Our Spark Plug Selection
We stock a wide range of marine spark plugs to cover all your needs, including:
- Standard spark plugs – affordable and dependable for routine use
- V-Power spark plugs – improved ignitability for better performance
- Iridium spark plugs – advanced durability and longer service life
- OEM-specific plugs – designed to fit Mercury, MerCruiser, and other popular marine engines
From Mercury outboards to MerCruiser sterndrives, our inventory includes the correct Mercury boat motor spark plugs to keep your engine running at peak efficiency.
When to Replace Your Spark Plugs
Most marine experts recommend inspecting and replacing spark plugs every season, or at least every 100 hours of operation. Signs that your plugs need replacement include difficulty starting, engine hesitation, reduced fuel efficiency, or visible carbon buildup on the electrodes. Swapping them out regularly is an inexpensive way to protect your boat engine and prevent costly repairs.
Shop Spark Plugs Online With Confidence
PowerBoatSupply.com makes it easy to find the exact boat spark plugs you need. With fast shipping, competitive pricing, and our decades of marine parts experience, we’re your trusted source for boat motor spark plugs and engine tune-up parts. Order today and get back on the water with confidence.