Best Fuel Injector Cleaner For Outboard Motor

#1 · Best Overall

1. Mercury Quickleen Cleaner

• Size: RM

Best for: Mercury Outboard Seasonal Care.

Why it ranks #1: Made by Mercury Marine to its original equipment specifications, listed for watercraft, and dosed at one ounce per five gallons for seasonal use.

Mercury’s occasional-use treatment rate—one ounce for five gallons of gasoline—makes Quickleen easy to add to a seasonal outboard routine. It targets carbon deposits on carburetors, injectors, intake valves, spark plugs, piston crowns, and cylinder heads, while its stated engine-protection benefits include preventing knocking and piston seize-up.

The broad list of treated engine areas makes this relevant when carbon buildup is the maintenance concern, rather than a product focused only on injectors. Mercury specifies occasional use throughout the season and a one-ounce-to-five-gallon gasoline rate, giving owners a clear dosing reference for routine fuel treatment. It is produced to Mercury Marine’s original equipment manufacturer specifications. Quickleen does not contain fuel stabilizers, so it does not cover fuel-breakdown prevention; Mercury recommends Quickare for that separate task.

Skip it if you need one additive to address fuel breakdown too; Mercury Quickare is listed for preventing fuel breakdown and oxidation.

Mercury outboard owners seeking an occasional in-season carbon treatment get a defined gasoline dose and broad deposit targets here. Choose a separate stabilizer for fuel breakdown; Quickleen itself does not contain one.

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

#2 · Frequent-Use Option

2. Quicksilver Quickleen Cleaner

• Size: 32 Fl Oz (Pack of 1)

Best for: Frequent Gas-Tank Treatment.

Why it ranks #2: Targets injector and carburetor deposits, works with gasoline and ethanol blends, and is listed for every fill-up at one ounce per five gallons.

Quicksilver Quickleen can be used at every fuel-tank fill-up, with one ounce treating five gallons of gasoline. That routine-friendly dosing pairs with compatibility across gasoline grades and ethanol blends, while the cleaner targets deposits in injectors and several other engine areas relevant to marine fuel-system maintenance.

Its stated fuel compatibility covers all grades of gasoline and ethanol-blend fuel, giving owners a treatment option across those gasoline types. The one-ounce-per-five-gallon rate and every-fill-up use guidance make recurring dosing straightforward to plan. Quickleen targets carbon deposits on injectors, carburetors, intake valves, spark plugs, piston crowns, and cylinder heads, and the product also states that it prevents engine knocking and piston seize-up. The 32-fluid-ounce bottle supplies a larger quantity for repeated treatments.

Skip it if you run a diesel outboard; Johnson Evinrude Fuel Systems Cleaner is also explicitly not for diesel, so choose a product specified for your fuel.

Choose Quickleen if your outboard runs gasoline, including ethanol blends, and you want a repeatable treatment at each fill-up. Its stated compatibility does not extend to diesel, so fuel type is the key boundary.

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

#3 · Cycle-Specific Pick

3. Johnson Evinrude Cleaner

• Weight: 2 lb

Best for: Johnson Evinrude Engine Owners.

Why it ranks #3: Factory-original Johnson Evinrude cleaner is listed for two- and four-cycle engines and directly addresses carbon deposits in injectors or carburetors.

Johnson Evinrude Fuel Systems Cleaner is specified for two- and four-cycle engines, giving owners of either cycle type a direct product match. Its instructions distinguish corrective carbon treatment from maintenance dosing, with separate fuel volumes for a malfunctioning injector or carburetor and for keeping those components in operating condition.

For an injector or carburetor malfunction attributed to carbon deposits, the supplied guidance calls for 16 ounces to treat 36 gallons. For ongoing maintenance, it gives 16 ounces for 72 gallons, providing two distinct dosing scenarios rather than one general rate. The product is not for diesel systems, which sets a clear fuel boundary. The description identifies it as a genuine Johnson Evinrude OMC factory-original part and specifies use in two-cycle and four-cycle engines.

Skip it if you run a diesel outboard; Sea Foam Motor Treatment is listed for diesel as well as gasoline and gas-ethanol blends.

Johnson Evinrude owners with two- or four-cycle engines get explicit rates for carbon-related problems and routine care. Keep its diesel restriction in mind, and follow the separate dosage guidance for each treatment situation.

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

#4 · Ethanol-Fuel Care

4. Quicksilver Quickare

• Size: 32 OZ
• Weight: 1.9 lb

Best for: Ethanol-Blended Fuel Maintenance.

Why it ranks #4: Marine-brand treatment targets gum and varnish while helping control corrosion and phase separation associated with ethanol-blended gasoline.

Quicksilver Quickare treats ethanol-related concerns including corrosion, gum and varnish buildup, and phase separation, making it a fit for recurring fuel maintenance. Its one-ounce-per-ten-gallon rate and every-fill-up use guidance give boat owners a simple routine for gasoline treatment.

Quickare’s stated reach includes fuel lines, tanks, carburetors, injectors, intake valves, and spark plugs, so the treatment addresses more than injector deposits alone. Its claims include helping control corrosion, gum, varnish, and phase separation associated with ethanol-blended gasoline. The one-ounce-per-ten-gallon rate allows recurring use at every fill-up, a practical contrast with occasional-use cleaners. Quicksilver lists all grades of gasoline as compatible, but the supplied details do not give a diesel-use claim.

Skip it if you need a stated corrective dose for carbon-related malfunction; Johnson Evinrude Fuel Systems Cleaner provides separate corrective and maintenance rates.

Quicksilver Quickare fits gasoline outboards receiving frequent ethanol-blend fuel, especially when recurring deposit and phase-separation control matters. It is specified for ongoing fill-up use, not as a separately dosed corrective carbon treatment.

Listed on Amazon as: Quicksilver Quickare Fuel Treatment

#5 · Storage Focus

5. STA-BIL Marine Tune-Up

• Weight: 7.5 oz

Best for: Storage-Focused Engine Protection.

Why it ranks #5: Its marine tune-up positioning and stated protection of internal components during storage make it a relevant seasonal option, though listing details are sparse.

STA-BIL Marine Tune-Up Fuel Treatment is specifically described as protecting internal components during storage, making that its clearest use case for an outboard owner. The supplied product information identifies an eight-ounce bottle, but offers little detail about a cleaner’s dose or particular injector-cleaning action.

The storage-protection claim gives this treatment a defined role when an engine is being put away, rather than establishing a routine injector-cleaning schedule. Its listed eight-ounce size identifies the bottle quantity, while the available details do not provide a fuel-treatment ratio or identify specific components it cleans. Buyers who need a quantified dose or stated targets such as injectors and carburetors should weigh that limited product information when choosing a marine fuel treatment.

Skip it if you need a stated injector target and gasoline dose; Mercury Quickleen specifies both component coverage and a one-ounce-per-five-gallon rate.

STA-BIL Marine Tune-Up is best considered by boat owners focused on internal-component protection during storage. The available details do not establish a dose or injector-cleaning claim, so it is a limited fit for dose-led cleaning routines.

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

#6

6. Sea Foam Motor Treatment

• Weight: 1 lb

Best for: Gasoline-and-Diesel System Cleaning.

Why it ranks #6: Cleans injectors, carburetor restrictions, and chamber areas in gasoline and diesel engines, but the listing does not establish outboard-specific compatibility.

Sea Foam Motor Treatment cleans the entire fuel system and is listed for gasoline, diesel, and gas-ethanol blends, giving it broad fuel compatibility. Its cleaning targets include injectors, carburetor restrictions, and chamber areas, while the supplied guidance calls for adding it every 3,000 miles.

The whole-system cleaning claim covers fuel residue and varnish as well as injectors, carburetor restrictions, and chamber areas, linking treatment to smoother idling and cleaner combustion. Compatibility with gasoline, diesel, and gas-ethanol blends makes it applicable across those listed fuel types. The stated 3,000-mile interval provides a maintenance schedule, though it is expressed in road-mile terms rather than outboard operating hours. This listing is a three-pack of 16-ounce bottles.

Skip it if you schedule outboard service by engine hours; Johnson Evinrude Fuel Systems Cleaner provides fuel-volume dosing rather than a mileage interval.

Sea Foam suits owners wanting a multi-fuel cleaner for residue, varnish, and several engine areas. Its stated maintenance interval uses road mileage, so outboard owners should consider that boundary when planning service.

Listed on Amazon as: Sea Foam Motor Treatment | Fuel & Oil Treatment | 16 oz, Pack of 3

#7

7. Red Line SI-1 Cleaner

• Size: 15 Fl Oz (Pack of 2)

Best for: Concentrated Multi-Area Cleaner.

Why it ranks #7: The concentrated cleaner targets injectors, carburetors, valves, and combustion-chamber deposits, but its listing does not specify marine or outboard use.

Red Line SI-1 combines high- and low-temperature detergents in a concentrated fuel-system cleaner, targeting deposits across injectors, carburetors, valves, and combustion chambers. That broad cleaning scope suits buyers looking beyond injectors alone, while its stated corrosion prevention adds a fuel-system protection function.

The concentrated detergent blend is specified to clean injector, carburetor, valve, and combustion-chamber deposits, so its stated reach spans multiple areas of a fuel system. Red Line also says SI-1 helps prevent corrosion and reduces gum and varnish buildup, addressing maintenance concerns beyond deposit removal. Its gasoline-stability benefit is relevant to fuel handling, and the formula includes synthetic upper-cylinder lubricant. The listing’s use instruction is truncated, however, so it does not provide a complete dose here.

Skip it if you need a fully stated dosing instruction; Mercury Quickleen gives a one-ounce-per-five-gallon gasoline rate.

Red Line SI-1 suits buyers seeking concentrated cleaning across several fuel-system areas plus corrosion and deposit control. The supplied instructions do not establish a complete dose, so check that limitation against your preferred treatment workflow.

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)

#8

8. Lucas Oil Fuel Treatment

• Size: 32 Fluid oz
• Weight: 898 g

Best for: Multi-Fuel System Lubrication.

Why it ranks #8: Treats gasoline and diesel and cleans and lubricates injectors, but the broad engine claims do not confirm suitability for a particular outboard.

Lucas Oil Fuel Treatment cleans and lubricates fuel-system components, including injectors, carburetors, and the combustion chamber. Its stated use with gasoline and diesel makes it a flexible option for owners maintaining different engine types, while the quart bottle provides a substantial supply for fuel-treatment use.

Lucas describes the treatment as cleaning and lubricating injectors, carburetors, and combustion chambers, linking deposit control with lubrication in the fuel system. It is listed for gasoline and diesel, so the same product category covers those two fuel types. The manufacturer also attributes improved fuel flow and reduced deposit buildup to increased power and acceleration, and says it burns excess exhaust emissions to improve fuel economy. The supplied information does not give a specific dose for outboard tanks.

Skip it if you want a clearly stated marine gasoline dose; Mercury Quickleen specifies one ounce for every five gallons.

Lucas Oil Fuel Treatment fits owners who value a multi-fuel cleaner and lubricant for injectors, carburetors, and combustion chambers. Since no outboard-specific dose is supplied, it is less straightforward for tank-by-tank marine dosing.

Listed on Amazon as: Lucas Oil 10003 Fuel Treatment – 1 Quart

#9

9. Rislone Hy-per Fuel Cleaner

• Size: 6 fl. oz, 1 Pack

Best for: Compact Injector-Cleaning Concentrate.

Why it ranks #9: Its listing includes water scooters and describes injector cleaning, but it does not specifically identify outboard motors or provide marine dosing.

Rislone Hy-per Fuel pairs injector cleaning with fuel-system lubrication in a six-ounce concentrate, targeting noisy injectors, rough idle, hard starts, and hesitation. Its stated compatibility includes gasoline, diesel, and E85, while the compact bottle suits buyers seeking a smaller-format treatment.

The cleaning and lubrication claims connect the product to symptoms such as noisy injectors, hard starting, rough idle, and hesitation, which the listing says it helps eliminate. Compatibility with gasoline, ULSD diesel, and E85 gives it broad fuel-type coverage. Rislone also says regular use in summer and winter maintains engine efficiency and power. The supplied details identify a six-fluid-ounce can but do not provide a treatment ratio, leaving out the dose needed to plan use in an outboard tank.

Skip it if you need a stated marine dosing ratio; Johnson Evinrude Fuel Systems Cleaner lists treatment volumes for two-cycle and four-cycle engines.

Rislone’s six-ounce concentrate suits owners seeking injector cleaning and lubrication across several fuel types. It is a less direct choice when precise outboard dosing is essential, because the supplied information gives no fuel-treatment ratio.

Listed on Amazon as: Rislone Hy-per Fuel Fuel Injector Cleaner Concentrate,Pack of 1

#10

10. Rislone 4732 Cleaner

• Size: 1 Count (Pack of 1)
• Weight: 8 oz

Best for: Larger-Bottle Injector Treatment.

Why it ranks #10: This larger 32-ounce general fuel-system treatment cleans injectors and includes upper-cylinder lubricant, but no outboard-specific application is listed.

Rislone 4732 pairs a 32-ounce bottle with upper-cylinder lubricant, giving buyers a larger-format injector cleaner that also addresses cylinder, ring, and piston wear. Its stated targets include noisy injectors, rough idle, hard starts, and hesitation, making it relevant to recurring fuel-system upkeep.

The larger bottle supplies more product than Rislone’s six-ounce concentrate, while the upper-cylinder lubricant adds a stated wear-prevention function for cylinders, rings, and pistons. The cleaner is described as helping eliminate noisy injectors and fuel pumps, rough idle, hard starting, and hesitation. Rislone recommends regular use in summer and winter to maintain efficiency and power. Although the product is identified for all gasolines and fuels in its supplied claims, no outboard-specific dose is provided.

Skip it if you prefer a smaller single-treatment format; Rislone Hy-per Fuel Cleaner Concentrate comes in a six-ounce can.

Rislone 4732 fits owners who want a larger injector-cleaner supply with upper-cylinder lubrication for regular upkeep. The supplied information does not give a marine tank dose, so confirm that the available guidance suits your routine.

Listed on Amazon as: Rislone 4732 Fuel Injector Cleaner with Upper Cylinder Lubricant, 32 oz