Compatible Applications

Mercury 8M0052939 / 8M0207794 is used in a broad range of Mercury Marine shift systems. The supplied Mercury fitment includes outboard, Verado, Pro XS, racing, sterndrive, inboard and TowSports applications.

Because the same switch is used across several different engine and shift systems, always verify the model, serial number and OEM part number.

Mercury / Mariner 3.0L Outboards

Mercury DFI, Pro XS and Sport XS Applications

Mercury Racing and Special Performance Applications

Mercury V6 2.5L Applications

Mercury Verado Applications

Mercury 75-115 HP EFI Applications

MerCruiser Sterndrive Applications

Mercury Diesel / CMD Applications

OEM and Cross Reference Numbers

Pro Marine Replacement Available

Pro Marine Neutral Safety Switch - 52939P

Pro Marine also stocks an aftermarket replacement switch for the same compatible Mercury Marine applications.

Choose between the genuine Mercury OEM switch and the Pro Marine 52939P aftermarket replacement.

View Pro Marine 52939P Neutral Safety Switch

What This Part is Used For

The neutral safety / shift position switch provides the engine or control system with information about the position of the shift mechanism.

On applications where it serves as a neutral safety switch, it is part of the starting-safety circuit that helps prevent the engine from starting while the transmission or gearcase is in gear.

Mercury also uses this switch in several mechanical and Digital Throttle and Shift (DTS) systems, which is why the same OEM switch appears in outboard, sterndrive, inboard and diesel applications.

Common Symptoms of a Neutral Safety or Shift Switch Problem

• Engine will not crank even though the control is in neutral
• Intermittent no-crank condition
• Engine starts only when the control lever is moved slightly
• Incorrect or inconsistent shift-position indication
• DTS or shift-related fault after other causes have been eliminated
• Physical damage to the switch or actuator
• Corrosion or damage at the electrical connector

These symptoms can also be caused by wiring, linkage adjustment, control-box problems or other starting-system components. Diagnose the system before replacing the switch.

Installation and Replacement Tips

• Disconnect battery power before servicing the shift or starting circuit.
• Confirm the OEM switch number before removing the original part.
• Note the position and adjustment of the original switch.
• Inspect the electrical connector and wiring for corrosion or damage.
• Inspect mechanical shift linkage for wear or improper adjustment.
• Install and adjust the switch according to Mercury service procedures.
• Verify proper forward, neutral and reverse operation after installation.
• Where applicable, verify the engine starts only in neutral.
• On DTS applications, follow the appropriate Mercury diagnostic procedure.

Key Features and Benefits

• Genuine Mercury Marine OEM component
• Mercury item number 8M0052939
• Current Mercury replacement number 8M0207794
• Fits numerous Mercury and Mariner outboard applications
• Fits select Mercury Verado and Pro Verado models
• Fits select Mercury Pro XS, XS and racing outboards
• Fits select MerCruiser sterndrive applications
• Fits select MerCruiser inboard and TowSports applications
• Used in mechanical and DTS-related shift systems depending on application
• Replaces earlier Mercury 889514A01 and 814281A7 numbers
• Pro Marine aftermarket version also available

FAQ

Is 8M0052939 a genuine Mercury part?
Yes. This listing is for the genuine Mercury Marine OEM switch.

What replaced Mercury 8M0052939?
Mercury has superseded 8M0052939 to 8M0207794.

Will 8M0207794 replace 8M0052939?
Yes. 8M0207794 is the current Mercury functional replacement for 8M0052939.

Does this replace 889514A01?
Yes. 889514A01 is an earlier Mercury part number in the replacement family.

Does this replace 814281A7?
Yes. 814281A7 is also an earlier Mercury number in the replacement chain.

Does this switch fit Mercury Verado?
Yes. The supplied fitment includes many 135-350 HP Verado applications, including 4-cylinder, 6-cylinder and Pro Verado models. Verify the serial range above.

Does it fit Mercury Pro XS?
Yes. The supplied Mercury data includes multiple Pro XS applications, including 2.5L and 3.0L models.

Does 8M0052939 fit MerCruiser?
Yes. The supplied Mercury fitment includes multiple MerCruiser sterndrive, inboard and TowSports applications, including 496 MAG, 5.0L MPI, 350 MAG, 377 MAG, 8.2L and CMD / TDI diesel models.

Is this strictly a neutral safety switch?
It is commonly used as a neutral safety / shift position switch, but Mercury uses the same switch in several different mechanical and DTS shift assemblies depending on the application.

Can I determine fitment by horsepower alone?
No. This switch covers many different Mercury engine families. Verify the model, serial number and OEM part number before ordering.

Do you carry an aftermarket version?
Yes. Pro Marine also stocks the Pro Marine 52939P Neutral Safety Switch .

Searchable Part Numbers

8M0052939, 8M0207794, 87-8M0052939, 87-8M0207794, 889514A01, 814281A7, 879150T94

Searchable Terms

Mercury OEM neutral safety switch, Mercury neutral switch, Mercury shift switch, Mercury shift position switch, Mercury outboard neutral safety switch, Mercury Pro XS shift switch, Mercury Verado shift switch, Verado neutral safety switch, Mercury DTS shift switch, MerCruiser neutral safety switch, MerCruiser shift switch, MerCruiser DTS switch, 8M0052939 switch, 8M0207794 switch

What is Type A1 Marine Fuel Hose?

Type A1 marine fuel hose is designed for fuel-feed applications requiring a marine hose with enhanced fire-resistant performance.

Type A1 hose is commonly used in permanent marine fuel systems and installations where the fuel line passes through enclosed or below-deck areas.

When selecting fuel hose, both the inside diameter and the required hose classification should be verified for the installation.

Why Use 1/2" Fuel Hose?

A 1/2" fuel line provides greater internal flow area than the more common 1/4", 5/16" and 3/8" marine fuel hoses.

It may be used in applications where the engine or fuel-system design requires a larger fuel supply line to support higher fuel-flow demand.

Always follow the engine or boat manufacturer's required hose diameter rather than increasing or decreasing hose size without verifying the fuel-system requirements.

Matching Fuel Hose Clamp

German-Style Hose Clamp - 4-4

Recommended hose clamp for the MPI 360-12 1/2" Type A1 marine fuel hose.

German-style hose clamps provide a secure connection for larger marine fuel-hose applications.

View German-Style Hose Clamp

Fuel Line Tools and Clamp Assortment

Oetiker Standard Jaw Pincer Tool

Useful installation tool for Oetiker ear clamps used throughout many marine fuel-line systems.

While this 1/2" hose uses the German-style clamp shown above, the pincer tool is useful when servicing other fuel-hose sizes that use Oetiker ear clamps.

View Oetiker Pincer Tool

Oetiker Clamp Pack with Tool

Complete assortment of common Oetiker clamp sizes with the installation tool included.

A convenient option for marine shops and technicians servicing different fuel-hose sizes throughout a boat or engine.

View Oetiker Clamp Pack

What This Fuel Hose is Used For

MPI 360-12 is used when building, repairing or replacing a marine fuel supply line requiring 1/2" Type A1 hose.

Typical applications involve larger marine fuel systems where increased fuel-flow capacity is required and the installation calls for Type A1 hose.

Typical 1/2" Fuel-Line Setup

Depending on the boat and engine, a 1/2" marine fuel-line installation may include:

• MPI 360-12 1/2" Type A1 marine fuel hose
• German-style 4-4 hose clamps
• Fuel tank pickup or shutoff valve
• Fuel/water separator or filter assembly
• Engine fuel-system connection
• Application-specific fittings and adapters

Primer Bulb vs. Larger Fuel Systems

Smaller outboard fuel systems commonly use 1/4", 5/16" or 3/8" hose with an inline primer bulb.

A 1/2" fuel supply line generally indicates a higher-flow fuel system, and a hand primer bulb is not normally part of that configuration.

The engine manufacturer's fuel-system requirements should always take priority when determining hose size, fittings, filters and priming components.

Fuel Hose Size Comparison

Key Features & Benefits

• 1/2" inside diameter
• MPI Products marine fuel hose
• Type A1 marine fuel-hose classification
• Designed for fuel-feed applications requiring Type A1 hose
• Suitable for higher-flow marine fuel systems
• Common choice for enclosed or below-deck fuel-line routing when 1/2" hose is required
• Matching German-style 4-4 hose clamp available
• Primer bulb normally not used with 1/2" fuel-line systems
• Fuel-system installation tools and clamp assortment available

Need Help Choosing the Right Marine Fuel Hose?

Fuel-line diameter, Type A or Type B classification, fuel-system flow requirements, fittings, filters and clamp selection all need to match the boat and engine installation.

Visit the Pro Marine Fuel Line Technical Center

FAQ

What size is MPI 360-12?
This fuel hose has a 1/2" inside diameter.

What type of fuel hose is 360-12?
It is Type A1 marine fuel hose.

What is Type A1 fuel hose used for?
Type A1 is used for marine fuel-feed applications requiring the additional fire-resistant performance associated with Type A hose.

Can this hose be used below deck?
Type A1 hose is commonly used in enclosed and below-deck fuel-system installations when the fuel system calls for this hose size and classification.

Which clamp fits this 1/2" hose?
Use the German-Style 4-4 Hose Clamp .

Does this hose use an Oetiker ear clamp?
The recommended clamp for this hose is the German-style 4-4 hose clamp.

Does 1/2" fuel hose use a primer bulb?
A primer bulb is not normally used in a fuel system requiring 1/2" hose. Larger lines are typically used in higher-flow fuel systems with a different priming and fuel-delivery arrangement.

Should I use 1/2" hose just to increase fuel flow?
Use the hose diameter specified for the engine and fuel system. Increasing hose size without verifying the complete system is not a substitute for following the manufacturer's fuel-system requirements.

Do you sell fuel-line clamp tools?
Yes. Pro Marine stocks the Oetiker Standard Jaw Pincer Tool for fuel-line applications using Oetiker ear clamps.

Do you sell a complete clamp assortment?
Yes. The Oetiker Clamp Pack with Tool includes commonly used clamp sizes and an installation tool.

Searchable Part Numbers & Terms

360-12, MPI 360-12, 1/2 fuel hose, 1/2 marine fuel hose, 1/2 boat fuel line, 1/2 Type A1 fuel hose, Type A1 marine fuel line, marine fuel supply hose, high flow marine fuel hose, large outboard fuel line, boat fuel hose, below deck fuel hose, enclosed marine fuel line, marine fuel line, German style hose clamp, 4-4 hose clamp, marine fuel hose clamp, bulk marine fuel hose, marine fuel system, fuel hose by the foot

What This Fuel Fill Hose is Used For

FILLHOSE-112 is intended for the fuel-fill portion of a permanently installed marine fuel system.

In a typical installation, the hose runs from the fitting directly behind the deck-mounted fuel cap down to the fuel tank's fill-neck connection.

Common applications include:

• Boat fuel tank fill hose
• Deck fill to fuel tank connection
• Replacement of aged or deteriorated marine fuel fill hose
• Boat restoration and fuel-system rerigging
• New permanent marine fuel tank installations

What Does USCG Type A2 Mean?

Type A2 is a marine fuel-hose classification used for compatible fuel-system applications including fuel fill and vent lines.

Under federal marine fuel-system requirements, Type A hose is constructed to meet a fire-resistance test. Type A2 is a Class 2 hose designation.

The important application distinction for this product is that Type A2 hose is suitable for a marine fuel fill or vent line. It should not be confused with the smaller Type A1 fuel hose commonly used in fuel-feed applications.

Matching 1-1/2" Fuel Fill Hose Clamp

German-Style Hose Clamp - 4-8

Matching clamp for the 1-1/2" fuel fill hose installation.

Pro Marine's 4-8 German-style clamp has a 27-51mm / 1.05-1.99" clamping range and is made from 316 stainless steel.

Secure the hose at the deck-fill fitting and fuel-tank fill neck according to the requirements of the installation.

View 4-8 German-Style Hose Clamp

1-1/2" Chrome Gas Deck Fill

Chrome 1-1/2" Gas Deck Fill - 3-5740

Universal 1-1/2" chrome gas deck fill for compatible marine fuel systems.

The fuel fill hose connects to the hose barb beneath the deck fill and routes gasoline down to the permanent fuel tank.

View 1-1/2" Chrome Gas Deck Fill

1-1/2" and 2" Fuel Fill Hose Options

Need 2" Fuel Fill Hose?

2" Type A2 Fuel Fill Hose - FILLHOSE-2

Larger Type A2 fuel fill hose for marine installations using a 2" tank fill and deck-fill connection.

View 2" Fuel Fill Hose

German-Style Hose Clamp - 4-9

Matching clamp option supplied for Pro Marine's 2" Type A2 fuel fill hose.

View 4-9 Hose Clamp

Fuel Fill Hose Installation Tips

• Match the hose inside diameter to the deck fill and fuel-tank fill connection.
• Use marine fuel hose specifically designed for fuel-fill applications.
• Use properly sized corrosion-resistant hose clamps.
• Make sure the hose is fully seated on each fitting before clamping.
• Avoid sharp bends that can restrict fuel flow while filling the tank.
• Route the hose so it cannot be crushed by batteries, storage or other equipment.
• Keep the hose away from sharp edges and moving components.
• Inspect the entire fill hose for cracking, hardening and deterioration.
• Check all connections for fuel seepage after installation.

When Should Marine Fuel Fill Hose Be Replaced?

Fuel fill hose should be inspected whenever the fuel tank, deck fill or surrounding rigging is serviced.

Consider replacement if you find:

• Cracking in the outer hose
• Dry, hardened or brittle hose
• Soft or swollen areas
• Abrasion or chafing
• Fuel odor around the fill-hose area
• Visible fuel seepage
• Damaged or heavily corroded clamps
• Hose that no longer fits securely on the fill fitting or tank

How the Marine Fuel Fill System Works

When gasoline is added through the deck-mounted gas cap, it travels through the large-diameter fuel fill hose and into the permanent fuel tank.

A separate fuel-tank vent system allows displaced air to escape while the tank is being filled.

The fuel fill hose, deck fill, tank connection and vent system all need to remain correctly routed and unobstructed for reliable refueling.

Key Features and Benefits

• 1-1/2" marine fuel fill hose
• USCG Type A2 hose
• Designed for deck-fill to fuel-tank applications
• Large diameter for marine fuel filling
• Matching 4-8 German-style clamp available
• Matching 1-1/2" chrome deck fill available
• 2" Type A2 fuel fill hose also available
• Useful for new fuel-system installations and replacement projects

FAQ

What size is FILLHOSE-112?
FILLHOSE-112 is 1-1/2" inside-diameter marine fuel fill hose.

What is this hose used for?
It connects the boat's deck-mounted fuel fill to the fill connection on the permanent marine fuel tank.

Is FILLHOSE-112 Type A2?
Yes. This hose is listed as USCG Type A2.

Can I use this as the fuel hose from the tank to the engine?
This product is intended as large-diameter fuel fill hose. Use the proper marine fuel-supply hose specified for the tank-to-engine portion of the fuel system.

Which clamp fits the 1-1/2" fuel fill hose?
Pro Marine pairs it with the 4-8 German-Style Hose Clamp .

Do you stock a 1-1/2" fuel deck fill?
Yes. Pro Marine stocks the 3-5740 Chrome 1-1/2" Gas Deck Fill .

Do you have 2" fuel fill hose?
Yes. Pro Marine also stocks FILLHOSE-2 2" Type A2 Fuel Fill Hose .

How do I know whether I need 1-1/2" or 2" hose?
Measure or verify the hose connection size on both the deck fill and the fuel tank. The replacement hose needs to match the fittings used in the boat's fuel-fill system.

Searchable Terms

FILLHOSE-112, 1-1/2 fuel fill hose, 1.5 inch fuel fill hose, Type A2 fuel hose, USCG Type A2 hose, marine fuel fill hose, boat gas fill hose, fuel tank fill hose, deck fill hose, gas tank filler hose, 4-8 hose clamp, 3-5740, FILLHOSE-2, marine fuel tank hose

What This Fuel Fill Hose is Used For

FILLHOSE-2 is intended for the fuel-fill section of a permanently installed marine fuel system.

In a typical installation, the hose connects the fitting underneath the deck-mounted gas fill to the fill neck on the fuel tank.

Common applications include:

• Boat fuel tank fill hose
• Deck fill to fuel tank plumbing
• Replacement of old or deteriorated fuel fill hose
• Boat restoration and fuel-system rerigging
• New permanent marine fuel-tank installations

What Does Type A2 Fuel Hose Mean?

Type A2 is a marine fuel-hose classification commonly used for fuel fill and vent applications.

The Type A designation indicates a hose intended for marine fuel systems where fire resistance is required. The A2 classification is used for specific fill and vent applications rather than the smaller engine fuel-feed line.

For this product, the important point is that it is designed as a large-diameter marine fuel fill hose.

Matching 2" Fuel Fill Hose Clamp

German-Style Hose Clamp - 4-9

Matching clamp for Pro Marine's 2" Type A2 fuel fill hose.

Use properly sized corrosion-resistant clamps to secure the fuel fill hose at the deck-fill fitting and fuel-tank connection.

View 4-9 German-Style Hose Clamp

1-1/2" and 2" Fuel Fill Hose Options

Need 1-1/2" Fuel Fill Hose Instead?

1-1/2" Type A2 Fuel Fill Hose - FILLHOSE-112

Smaller Type A2 marine fuel fill hose for installations using 1-1/2" deck-fill and fuel-tank connections.

View 1-1/2" Fuel Fill Hose

German-Style Hose Clamp - 4-8

Matching clamp for the 1-1/2" Type A2 fuel fill hose.

View 4-8 Hose Clamp

1-1/2" Chrome Gas Deck Fill

1-1/2" Chrome Gas Deck Fill - 3-5740

Pro Marine also stocks a 1-1/2" chrome deck fill for compatible marine fuel systems using 1-1/2" fill hose.

This deck fill is not the matching 2" connection for FILLHOSE-2, but it is available for installations using the smaller 1-1/2" hose system.

View 1-1/2" Chrome Gas Deck Fill

How a Marine Fuel Fill System Works

The fuel-fill system provides the path from the deck-mounted fuel cap to the boat's permanent fuel tank.

During refueling:

1. Fuel enters through the deck fill.
2. The fuel travels through the large-diameter fill hose.
3. The hose delivers the fuel to the tank's fill connection.
4. The tank's separate vent system allows displaced air to escape.

The deck fill, fuel fill hose, tank connection and vent system all need to be correctly sized and routed for reliable filling.

Fuel Fill Hose Installation Tips

• Verify the deck-fill and tank-fill connection size before ordering hose.
• Use hose specifically rated for marine fuel-fill service.
• Make sure the hose fully seats over each hose barb or fitting.
• Use properly sized corrosion-resistant clamps.
• Avoid tight bends and kinks that can restrict fuel flow.
• Plan the routing before cutting the hose.
• Keep the hose away from sharp edges and moving parts.
• Do not allow batteries or stored equipment to crush the hose.
• Check both ends for leaks or seepage after installation.

Why Fuel Fill Hose is So Heavy Duty

Fuel fill hose is much larger and more heavily constructed than the smaller fuel hose used to feed an engine.

It has to handle:

• Large volumes of fuel during refueling
• Marine vibration and movement
• Fuel exposure
• Heat and environmental exposure
• The bends required between the deck fill and fuel tank

Because of its construction, fuel fill hose can be relatively stiff. Planning the routing before installation is especially important.

When Should Fuel Fill Hose Be Replaced?

Inspect the fill hose whenever the deck fill, fuel tank or surrounding rigging is serviced.

Replace the hose if you find:

• Cracks in the outer surface
• Hard, dry or brittle rubber
• Soft or swollen areas
• Abrasion or chafe damage
• Fuel seepage
• Persistent gasoline odor near the hose
• Loose, damaged or corroded clamps
• A hose that no longer fits tightly on the fittings

Key Features and Benefits

• 2" marine fuel fill hose
• Type A2 construction
• Designed for deck-fill to fuel-tank plumbing
• Large-diameter marine fuel-system application
• Matching 4-9 German-style clamp available
• 1-1/2" Type A2 fuel fill hose also available
• Suitable for replacement and new fuel-system installations
• Helps provide a dedicated path from the deck fill to the fuel tank

FAQ

What size is FILLHOSE-2?
FILLHOSE-2 is 2" inside-diameter marine fuel fill hose.

What is FILLHOSE-2 used for?
It is used to connect a compatible deck-mounted fuel fill to the fill connection on a permanent marine fuel tank.

Is this a Type A2 hose?
Yes. FILLHOSE-2 is a Type A2 marine fuel fill hose.

Can I use this as the fuel-supply line to the engine?
This product is intended as large-diameter fuel fill hose. Use the correct marine fuel-supply hose for the tank-to-engine fuel line.

Which clamp fits this hose?
Pro Marine pairs FILLHOSE-2 with the 4-9 German-Style Hose Clamp .

Do you have a smaller fuel fill hose?
Yes. Pro Marine also stocks FILLHOSE-112 1-1/2" Type A2 Fuel Fill Hose .

How do I know whether I need 1-1/2" or 2" hose?
Verify the hose-barb diameter on both the deck fill and the fuel tank. The hose size needs to match the fittings used in the boat.

Why is fuel fill hose so stiff?
Marine fuel fill hose is heavily constructed for its application, which makes it less flexible than smaller engine fuel hose. Plan bends and hose routing before installation.

Searchable Terms

FILLHOSE-2, 2 inch fuel fill hose, Type A2 fuel hose, marine fuel fill hose, boat gas fill hose, deck fill hose, fuel tank fill hose, marine gas tank hose, rigid fuel fill hose, 4-9 hose clamp, FILLHOSE-112, 1-1/2 fuel fill hose, boat fuel hose, marine fuel tank plumbing