Xiaoyudou 1-1/2" NPT Marine Fuel Cap 0540DPG99A — Vented Perko-Style Replacement, O‑Ring & Chain Kit

The Xiaoyudou 0540DPG99A is a 1-1/2" NPT threaded vented marine fuel cap kit made to replace Perko-style deck fills and maintain a watertight, pressure-stable fuel system.

Built for boats using angled 1-1/2" NPT vented deck fills, this replacement gas cap kit includes the cap, O-ring, wrench and safety chain so you have everything needed at installation. It recreates the venting function required by many non-EPA sealed systems to prevent vacuum locks and excessive pressure while resisting corrosion in harsh marine conditions.

Will this cap fit my Perko-style deck fill?

Yes — the 0540DPG99A is made to match several Perko deck fill figure numbers. It is specifically for vented 1-1/2" angled-neck fills using NPT threads, not BSP or sealed EPA systems.

• Compatible with Perko figure numbers 0540, 0541, 0556 and 0557
• Uses 1-1/2" NPT (National Pipe Thread) standard
• Not compatible with British Standard Pipe (BSP) threads
• Unsuitable for closed EPA-compliant sealed fuel systems

How does the vent and seal design protect my fuel system?

This cap combines a gasketed, watertight seal with an integrated venting path that equalizes tank pressure during normal operation. The design helps prevent fuel spillage from pressure buildup and reduces the chance of vapor lock or fuel starvation caused by vacuum conditions.

• O-ring ensures a secure waterproof closure at the deck fill
• Venting structure stabilizes internal tank pressure while underway
• Helps avoid vacuum lock and pressure-induced leaks
• Intended for vented marine fuel tanks, not sealed systems

What’s included and how easy is installation?

The kit is supplied with the replacement cap, a matching O-ring, a simple wrench for tightening and a chain to retain the cap on deck. Installation is straightforward for anyone familiar with threaded deck fills and basic marine maintenance.

• Complete kit: cap, O-ring, wrench and chain included
• Threaded 1-1/2" NPT connection screws into existing angled neck fill
• Use the supplied wrench to achieve correct torque without damaging threads
• Chain anchors cap to deck to prevent loss while fueling or underway

How durable is this replacement cap for saltwater use?

Manufactured from high-strength, corrosion-resistant materials, the cap is intended to withstand marine exposure, wear and repeated use. Its construction focuses on long-term durability where salt, sun and vibration are common.

• High-strength materials offer corrosion and wear resistance
• Durable finish reduces maintenance and extends service life
• Designed for the mechanical demands of boating environments
• Regular inspection and O-ring replacement extend reliability

Who this is for: Owners of boats with vented 1-1/2" NPT angled neck Perko-style deck fills who need a complete, corrosion-resistant replacement kit. Choose this Xiaoyudou model if you require a vented cap (not for sealed or BSP-threaded systems), want an included O-ring and wrench for immediate installation, and prefer a cap built to resist marine wear.