Best Marine Fuel Injector Cleaner for Boat Engines

#1 · Best Overall

1. STA-BIL 360 Marine Treatment

• Weight: 1.9 lb
• Volume: 139 cubic in
• Size: 32 Fl Oz (Pack of 1)

Best for: Whole-system marine treatment.

Why it ranks #1: Its marine formula uses PEA additives to clean injectors, lines, and fuel pumps; the 32-ounce bottle dose is 1 ounce per 10 gallons.

STA-BIL 360 Marine uses PEA additives to clean injectors, lines, and fuel pumps as part of a whole-system treatment. Its listed functions also include removing water, gum, and varnish while providing corrosion protection, making it relevant to owners combining in-season cleaning with component care.

The PEA formula is described as reaching injectors, lines, and fuel pumps, so its cleaning scope extends beyond the injector itself. The directions state that one ounce treats up to 10 gallons, and the bottle includes a small-cap squeeze measure plus side measurements for larger quantities; those details support repeat dosing without a separate measuring tool. Its stated corrosion protection and in-season use also suit owners who want cleaning paired with protection for internal fuel-system parts.

Skip it if you need explicit carbon targets for valves and cylinder heads; Quicksilver Quickleen names those engine areas.

Choose STA-BIL 360 Marine for in-season fuel-system cleaning that includes lines and pumps, with dosing built into the bottle. Its stated rate requires scaling the amount to fuel volume, so plan accordingly for larger tanks.

Listed on Amazon as: STA-BIL 360 Marine Fuel System Treatment, 32 oz

#2 · Best Carbon Cleaner

2. Mercury Quickleen Engine Cleaner

• Size: RM

Best for: Seasonal carbon deposit cleaning.

Why it ranks #2: Made by Mercury Marine to its OEM specifications, it removes carbon from injectors and other engine parts; 1 ounce treats 5 gallons.

Mercury Quickleen specifies one ounce for every five gallons of gasoline, giving boat owners a clear occasional-in-season treatment rate. It targets carbon deposits across injectors and several other engine areas, while its stated cautions distinguish cleaning from fuel stabilization.

The listed treatment rate makes seasonal use easier to plan: one ounce treats five gallons of gasoline, and the product is described for occasional use throughout the season. Its carbon-removal targets include injectors, carburetors, intake valves, spark plugs, piston crowns, and cylinder heads, addressing more than the injector alone. Mercury also states that Quickleen does not contain fuel stabilizers and points to Quickare for fuel breakdown and oxidation prevention, so storage protection requires a separate product.

Skip it if you need one product for storage stabilization too; Sea Foam Marine PRO explicitly helps stored fuel resist evaporation and gum formation.

Mercury Quickleen suits watercraft owners wanting measured, occasional in-season carbon cleaning across multiple engine components. Account for its explicit lack of fuel stabilizer, and use separate fuel-preservation protection when preparing for storage.

Listed on Amazon as: Mercury 8M0047931 Quickleen Engine & Fuel System Cleaner, 12 oz

#3 · Largest Bottle

3. Quicksilver Quickleen Cleaner

• Volume: 32 fluid oz
• Size: 32 Fl Oz (Pack of 1)

Best for: Frequent-fill carbon cleaning.

Why it ranks #3: This 32-fluid-ounce cleaner is specified for gasoline and ethanol-blend fuel and can be used at every fill-up at 1 ounce per 5 gallons.

Quicksilver Quickleen can be used at every fuel-tank fill-up, with one ounce treating five gallons of gasoline, giving frequent-use boat owners a clear routine. It works with all grades of gasoline and ethanol-blend fuel and lists carbon targets across multiple engine components.

The every-fill-up guidance pairs with the one-ounce-per-five-gallon rate to make repeated dosing simple to plan around refueling. Its compatibility with all grades of gasoline and ethanol-blend fuel broadens the listed fuel types it can accompany. The cleaner targets carbon deposits in injectors, carburetors, intake valves, spark plugs, piston crowns, and cylinder heads, and is also stated to prevent engine knocking and piston seize-up. The 32-fluid-ounce bottle supports a larger supply for that routine.

Skip it if you only need occasional seasonal cleaning; Mercury Quickleen is described for occasional use throughout the season rather than every fill-up.

Quicksilver Quickleen fits owners who want a repeatable cleaner at refueling and use gasoline, including ethanol blends. Its every-fill-up routine and five-gallon dose suit regular maintenance, while occasional-use buyers may prefer a less frequent schedule.

Listed on Amazon as: Quicksilver Quickleen Engine and Fuel System Cleaner

#4 · Best Storage Blend

4. Sea Foam Marine PRO

• Weight: 4.45 lb

Best for: Marine cleaning and storage.

Why it ranks #4: The marine treatment works through injectors and carburetors while helping stored fuel resist evaporation and prevent gum and varnish.

Sea Foam Marine PRO combines cleaning through injectors and carburetors with help for stored fuel to resist evaporation, giving boat and personal-watercraft owners a dual-purpose treatment. The listing also identifies a three-pack of 20-ounce containers for ongoing marine-system use.

Marine PRO works through injectors and carburetors and is described as removing harmful residues from fuel passageways, intake valves, pistons, and chamber areas. That broad cleaning scope supports maintenance beyond the injector alone. Its separate storage role helps fuel resist evaporation, preserve ignition vapors, and prevent gum and varnish formation, making it relevant before downtime as well as during operation. The three 20-ounce containers provide a multi-container supply, though the supplied details do not state a treatment rate.

Skip it if you need a stated dose for each tank; Mercury Quickleen specifies one ounce per five gallons of gasoline.

Marine PRO suits boat and jet-ski owners seeking both fuel-system cleaning and help preserving stored fuel. The three 20-ounce containers support ongoing use, but buyers who need precise per-tank dosing will need a stated rate.

Listed on Amazon as: Sea Foam Marine PRO Fuel System Treatment, 20 oz, Pack of 3

#5

5. STA-BIL Marine Tune-Up

• Weight: 7.5 oz

Best for: Marine storage protection.

Why it ranks #5: This marine-specific fuel treatment is positioned to protect internal components during storage, though the supplied details do not give an injector-cleaning dose.

STA-BIL Marine Tune-Up highlights protection for internal components during storage, making that stated benefit its clearest role for boat owners planning downtime. The supplied listing offers little detail about injector-cleaning action or dosing, so it is better approached as a storage-minded treatment than a specification-rich injector cleaner.

The internal-component storage protection is relevant when a marine engine will sit between outings, helping the buyer prioritize preservation during downtime. The listing identifies an 8-ounce bottle and a compact 6-by-3-by-3-inch product size, which gives a sense of its handling and storage footprint. However, the supplied facts do not state a treatment rate or name specific deposits it removes, so buyers seeking a measured injector-cleaning routine should look for those details elsewhere.

Skip it if you want stated carbon-removal targets or a dose; Mercury Quickleen specifies deposit targets and one ounce per five gallons.

This STA-BIL option fits boat owners prioritizing internal-component protection while an engine is stored. It is a limited-information pick for injector cleaning: the supplied listing does not specify a dose or particular deposits addressed.

Listed on Amazon as: STA-BIL Marine Tune-Up Fuel Treatment, 8 oz

#6 · Most Concentrated

6. Star Tron Injector Cleaner

• Weight: 4.8 oz
• Volume: 4 fluid oz
• Size: 1 Count (Pack of 1)

Best for: Concentrated gasoline treatment.

Why it ranks #6: The 4-ounce concentrated bottle treats 40 gallons, with directions of 1 fluid ounce per 10 gallons and treatment every four to five tanks.

STAR BRITE Star Tron Fuel System and Injector Cleaner treats 40 gallons with its 4-ounce concentrated formula, giving owners a stated coverage figure for planning repeat maintenance. Its directions call for one fluid ounce per 10 gallons every four to five tanks or as needed.

The stated one-ounce-per-10-gallon rate and 40-gallon treatment capacity make the small 4-ounce bottle straightforward to allocate across fuel loads. Star brite also recommends treatment every four to five tanks or as needed, giving owners a maintenance interval rather than an undefined schedule. The supplied facts identify it as a gasoline fuel-system and injector cleaner, while broader Star Tron claims about ethanol and water relate to a separate enzyme treatment and should not be assumed for this cleaner.

Skip it if you need carbon-removal targets spelled out; Mercury Quickleen names deposits on injectors, valves, plugs, pistons, and cylinder heads.

Star Tron fits owners seeking a compact, measured gasoline-system maintenance treatment with a stated tank interval. Keep its supplied claims distinct from other Star Tron products, and choose another cleaner if named deposit targets are essential.

Listed on Amazon as: STAR BRITE 096604 Star Tron Fuel System and Injector Cleaner – 4 oz.

#7

7. Liqui Moly Marine 4T Additive

• Weight: 7.84 oz
• Volume: 200 ml
• Size: 1 Count (Pack of 1)

Best for: Port-injected and carbureted engines.

Why it ranks #7: Its marine 4T additive is described for port-injected and carbureted gasoline engines and cleans injectors while protecting against corrosion.

Liqui Moly Marine 4T Additive Shooter is specified for port-injected and carbureted gasoline engines, where it cleans injectors and combustion-chamber deposits. The product also states that it restores proper fuel atomization and protects against corrosion, linking cleaning with fuel-system upkeep.

Its stated compatibility with port-injected and carbureted gasoline engines helps narrow the fit for owners of those engine types. The cleaner targets injectors, intake valves, and combustion-chamber carbon deposits, while the stated atomization benefit connects the treatment to fuel delivery. Corrosion protection adds a maintenance function alongside cleaning. The listing identifies a 200 ml liquid container, but provides no per-gallon treatment rate, so buyers will need to follow the product's own supplied directions for dosing.

Skip it if you need a measured dose for each tank; Mercury Quickleen specifies one ounce per five gallons of gasoline.

Liqui Moly suits owners of port-injected or carbureted gasoline engines seeking injector, valve, and combustion-chamber cleaning with stated corrosion protection. The supplied details do not give a dose per gallon, so account for that when planning treatment.

Listed on Amazon as: Liqui Moly Marine 4T Additive Shooter | 200 ML | SKU: 25102

#8

8. Johnson Evinrude Fuel Cleaner

• Weight: 2 lb

Best for: Two- and four-cycle cleaning.

Why it ranks #8: This genuine Johnson Evinrude cleaner is listed for two- and four-cycle engines, but its description says it is not for diesel systems.

Johnson Evinrude Fuel Systems Cleaner is listed for two- and four-cycle engines, giving owners in either category a specified marine cleaner option. Its supplied guidance describes treatment for carbon deposits and gives separate rates for addressing a malfunction and maintaining an injector or carburetor.

The listing states that a 16-ounce bottle treats 36 gallons when carbon deposits are causing injector or carburetor malfunction, or 72 gallons for maintaining operating condition. Those two rates help distinguish corrective treatment from ongoing maintenance. It is identified for both two-cycle and four-cycle engines, extending its stated fit across those engine types. The listing explicitly says not to use it on diesel systems, so it is limited to the stated engine applications and should not be selected for diesel fuel equipment.

Skip it if you operate a diesel engine; none of the listed gasoline-focused choices is a substitute for a diesel-specific treatment.

This BRP cleaner fits owners of two- or four-cycle engines seeking stated carbon-deposit treatment guidance for injectors or carburetors. Its explicit diesel restriction is decisive, so keep it to the listed non-diesel applications.

Listed on Amazon as: Johnson Evinrude Fuel Systems Cleaner 12-oz- 2 or 4 Cycle

#9

9. Seafoam IC5 Cleaner

• Weight: 5.6 oz

Best for: Gasoline injector maintenance.

Why it ranks #9: It is specifically formulated to clean gasoline fuel injectors and help restore spray patterns, but the supplied details do not identify it as marine-specific.

Sea Foam IC5 targets injector spray patterns in gasoline fuel-injected engines, giving owners a focused option when dirty injectors are associated with lost power or fuel economy. Its stated purpose is to clean injectors and help recover those performance measures, rather than serve as a broad marine storage treatment.

The gasoline fuel-injection limitation makes IC5 a focused choice for compatible engines, while its injector-cleaning action addresses deposits that can disrupt spray patterns. The product description connects cleaner injectors with recovering lost engine power and fuel economy, so it suits routine attention to those symptoms. No treatment rate or storage-stabilizing function is specified in the supplied details; buyers needing measured dosing guidance or seasonal fuel protection should compare products that provide those capabilities.

Skip it if you need a stated dose or storage protection; STA-BIL Marine Tune-Up explicitly notes protection for internal components during storage.

Choose IC5 if your gasoline fuel-injected engine needs injector-focused cleaning tied to lost power or economy. Its listed scope is narrower than a complete storage treatment, and no dosing rate is supplied in the product details.

Listed on Amazon as: Seafoam IC5 Fuel Injector Cleaner

#10

10. Red Line SI-1 Cleaner

• Volume: 15 fluid oz
• Size: 15 Fl Oz (Pack of 2)

Best for: Broad gasoline-system cleaning.

Why it ranks #10: This gasoline system cleaner addresses injectors and deposits, including GDI injectors, but the supplied product details do not establish marine-engine suitability.

Red Line SI-1 combines high- and low-temperature detergents to clean injectors, carburetors, valves, and combustion-chamber deposits, making it a broad gasoline-system option. Its listing also notes corrosion prevention, enhanced gasoline stability, and a two-bottle, 15-ounce-each package.

The detergent blend addresses deposits across injectors, carburetors, valves, and combustion chambers, giving buyers a treatment with targets beyond fuel injectors alone. Red Line also states that SI-1 helps prevent corrosion and enhances gasoline stability while reducing gum and varnish buildup, connecting cleaning with fuel-system upkeep. The listed 15-ounce, two-pack provides two containers for planned maintenance. Additional supplied facts include injector cleaning across forms, including GDI, and a synthetic upper-cylinder lubricant.

Skip it if you need a specified dose per gallon; Mercury Quickleen states one ounce for five gallons of gasoline.

Red Line SI-1 suits owners seeking broad gasoline-system cleaning, including GDI injectors, plus stated corrosion and deposit-control benefits. Its supplied details omit a treatment rate, so buyers who dose by tank volume may prefer a product with explicit directions.

Listed on Amazon as: Red Line 60103 SI-1 Complete Fuel System Cleaner, Cleans and Prevents Corrosion in Fuel Systems, Cleans Injectors, Carburetors, Valve and Combustion Chamber Deposits – 15 Ounce (2 Pack)