Ronybuy Fuel Pump Relay Kit — 12V Waterproof 40A Bypass Harness with 10 AWG

Ronybuy Electric Fuel Pump Relay Kit is a waterproof, heavy-duty 40A relay and harness designed to bypass stock fuel pump wiring and safely supply a dedicated 12V feed for consistent pump performance.

This universal 12-volt relay bypass harness (fits OEM P/N 30247 replacements) simplifies adding a dedicated power feed to an electric fuel pump. It routes a full-capacity 10-gauge power lead from the battery through a 30A inline fuse and 40A relay to the pump, reducing voltage drop and protecting stock circuits. All wires are color-coded and a wiring diagram is included for straightforward, reliable installation in cars, trucks, or custom fuel setups.

How does this kit improve fuel pump power delivery?

The Ronybuy kit places a high-current relay between the battery and the pump so the pump gets full 12V without running heavy current through thin factory wires or switches. That lowers heat and voltage loss and helps the pump maintain steady pressure during high-demand conditions. It also uses 10 AWG wiring to handle up to 40 amps safely.

• 40A relay controls the high-current feed while a small trigger activates it
• 10-gauge red lead from battery provides low-resistance power
• 30A inline fuse protects the circuit at the source
• Color-coded wires speed installation and reduce wiring errors

What components are included and how are they assembled?

The kit ships complete with a waterproof 40A relay, relay socket with harness pre-wired, an inline waterproof fuse holder with a 30A fuse, mounting hardware, heat-shrink connectors, and cable ties. Everything needed to install the relay and connect to the factory pump trigger is included so you won’t need to source additional parts. The harness wires are long to accommodate engine bay or chassis mounting choices.

• 1x 40A waterproof relay and 1x relay base with full harness
• 1x inline waterproof fuse holder and 1x 30A fuse
• Mounting screws, heat-shrink ring terminals, and wire connectors
• 10 ft red (10 AWG), 6 ft orange (10 AWG), 2 ft brown (16 AWG), 4 ft black (16 AWG)

Is this kit durable enough for harsh environments and long-term use?

Yes — the relay and fuse holder are rated waterproof and the wiring harness uses heavy-gauge cable and rugged connectors for elevated heat and vibration resistance. The included heat-shrink terminals and cable ties help create moisture-resistant, strain-relieved terminations. Ronybuy backs the product with a 2-year coverage and a 45-day money-back option for peace of mind.

• Waterproof relay and inline fuse holder for wet locations
• Heavy-gauge 10 AWG power wires resist voltage drop and heat
• Heat-shrink terminals improve corrosion resistance at connections
• Includes mounting hardware for secure relay placement

How easy is it to install this relay kit in my vehicle?

Installation is designed to be plug-and-play for anyone familiar with basic automotive wiring: connect the red 10-gauge to the positive battery terminal, ground the black wire to chassis, hook the brown trigger to the pump’s 12V signal, and run the orange output to the pump. A clear wiring diagram in the package shows each connection and color code. Typical installs require only hand tools and basic electrical crimping skills.

• Color-coded wires and diagram included for straightforward hookup
• Pre-wired relay base reduces on-site wiring complexity
• Long wires accommodate diverse mounting locations
• Simple battery, ground, trigger, and pump connections

Who is this for: Ronybuy’s 12V 40A electric fuel pump relay kit is aimed at mechanics, DIY tuners, and vehicle owners upgrading pumps or building custom fuel systems who need a reliable high-current feed. It’s useful for replacing worn OEM relay assemblies (P/N 30247), reducing voltage drop in high-demand setups, or adding a safe bypass harness where the factory wiring is undersized. If you want a rugged, waterproof relay harness with clear wiring, long leads, and all necessary fittings included, this kit provides a complete, install-ready solution.