Gas Cap

What This Gas Deck Fill is Used For

The deck fill provides the exterior opening used to add gasoline to a boat's permanently installed fuel tank.

During refueling, gasoline passes through the deck fill and then travels through the large-diameter marine fuel fill hose to the tank.

Typical applications include:

• Replacement of an old or damaged marine gas fill
• Boat restoration projects
• Permanent marine fuel-tank installations
• Replacement of corroded or worn deck-fill hardware
• Fuel-system rerigging using 1-1/2" fill hose

Matching 1-1/2" Type A2 Fuel Fill Hose

Matching Fuel Fill Hose Clamp

How the Deck Fill and Fuel Fill Hose Work Together

The deck fill, fill hose and fuel tank form the main refueling path in a permanent marine fuel system.

1. The fuel nozzle is inserted into the deck fill.
2. Fuel enters through the 1-1/2" fill connection.
3. The Type A2 fuel fill hose carries fuel toward the tank.
4. The tank receives the fuel through its fill-neck connection.
5. The separate fuel-tank vent system allows displaced air to escape.

Correct hose sizing and smooth routing help the tank accept fuel more consistently during refueling.

Need 2" Fuel Fill Hose?

Some marine fuel systems use a larger 2" fill-hose connection. Pro Marine also stocks the 2" Type A2 fuel fill hose and matching 4-9 clamp.

Deck Fill Installation Tips

• Verify the hose connection diameter before replacing the deck fill.
• Use marine fuel hose intended for the fuel-fill application.
• Make sure the fill hose fully seats over the deck-fill connection.
• Use properly sized corrosion-resistant hose clamps.
• Avoid sharp bends immediately below the deck fill.
• Keep the fill hose away from sharp edges and moving components.
• Inspect nearby hose for cracking, swelling or abrasion.
• Make sure the deck fill is securely mounted and sealed to the deck.
• Check the complete system for fuel seepage after installation.

When Should a Marine Gas Deck Fill Be Replaced?

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

Replacement may be appropriate if you find:

• Corrosion or physical damage
• A damaged or difficult-to-use cap
• A loose deck mounting
• Damage at the hose connection
• Fuel odor or seepage around the fitting
• Worn sealing surfaces

Key Features and Benefits

• 1-1/2" marine gas deck fill
• Chrome finish
• Universal marine application
• Moeller brand
• Aftermarket fuel-system component
• Cross reference 39729357409
• Pairs with 1-1/2" Type A2 fuel fill hose
• Matching 4-8 German-style clamp available
• 2" Type A2 fuel fill hose option also available

FAQ

What size hose connection does 3-5740 use?
This deck fill is designed for a 1-1/2" fuel fill hose.

Who manufactures 3-5740?
Pro Marine lists this deck fill as a Moeller aftermarket product. :contentReference[oaicite:0]{index=0}

What is the cross-reference number?
The listed cross reference is 39729357409. :contentReference[oaicite:1]{index=1}

Is this a universal application?
Yes. Pro Marine lists 3-5740 as a universal marine gas deck fill. :contentReference[oaicite:2]{index=2}

What hose should I use with it?
For a compatible 1-1/2" installation, use FILLHOSE-112 1-1/2" Type A2 Fuel Fill Hose .

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

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

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Shipping Policy

• Free shipping on orders over $100 continental U.S.
• Orders ship via UPS, USPS, and FedEx.
• Orders received before 5:30 PM EST ship the same business day.
• Typical delivery time is 1-5 business days.

30-Day Return Policy

• Returns accepted within 30 days of delivery.
• Parts must be new, unused, and in original packaging.
• Installed parts are not returnable.
• Return authorization is required before sending items back.

Need help with a return or order question?
Contact Us
Phone: 941-721-3000

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