Installing an in-tank fuel pump kit in the FD3S

An in-tank fuel pump kit can improve delivery and reliability in an FD3S, especially with turbocharging, larger injectors or hot Australian weather. The pump, regulator, sender and wiring must work as a matched system, not as a simple bolt-in upgrade.

Australian RX-7s are commonly right-hand drive, although imported left-hand-drive examples also exist. Check pump orientation, connector position and line routing against the exact car. Use the specified unleaded petrol, including E10 where approved, and confirm ethanol compatibility rather than assuming every petrol pump will tolerate blends.

Prices are usually in Australian dollars and include GST, while freight matters in regional New South Wales, Queensland or Western Australia. Compare landed costs and warranty support from Melbourne, Brisbane or Perth sellers, and document the work for roadworthiness and insurance. If a seller cannot provide clear pump figures, give it a miss.

Confirm the fitment before buying the kit

Treat the chassis and tank variation as more important than the 13B or 20B badge. Match the kit to the FD3S tank, module geometry, lift-pump arrangement and 12-volt supply; injector size alone does not justify a high-current pump.

Check advertised pressure and flow against the factory manual, then measure the existing motor’s draw. Record peak current, duty cycle, priming needs and whether the assembly is returnless or recirculating. A listing for an FC or another RX-7 generation is not an FD3S match.

Good workshop practice is to inspect and measure before replacing parts, much like the checks in chain and sprocket care. Verify dimensions, condition and operating limits, and reject any listing that cannot explain its application.

Prepare the car and a safe fuel-handling area

Before opening anything, gather the references and record the original arrangement:

• Photograph the module, connector, hoses and line routing before disturbing them.
• Obtain the FD3S service manual, wiring diagram and specified gasket or seal.
• Confirm pump voltage, peak current, pressure, flow and module compatibility.
• Arrange approved fuel containers, rated tools and any missing terminals or hose.

Set up the work area with these essentials:

• Release residual pressure at the test port with suitable equipment, then cap the lines.
• Disconnect the negative battery terminal before opening the tank.
• Use ventilation, an approved petrol-rated extinguisher and a no-smoking area.
• Keep phones away, control static and collect spilled fuel for proper disposal.

Access details can differ, so consult the manual before removing trim. If the rear seat must come out, protect the upholstery and clips; RX-7 seat reupholstery explains the construction. Photograph fastener and plug positions, then refit brittle trim without force.

Match the pump arrangement to the fuel system

The label on a kit may hide major differences. Establish whether it replaces the whole module, only the motor, or uses an external regulator, and how the FD3S return and warning connections are handled.

Arrangement	Fuel path	Must match	Main concern
Factory-style module	Original tank-side layout	Pressure, current and sender geometry	A high-flow pump may still overload the system
Complete returnless module	One-way outlet to the fuel rail	Regulator setting and return capping	Incorrect capping or fittings
External-regulator kit	Tank pump feeds a separate regulator	Hose rating and mounting location	Heat, vibration and extra plumbing

Returnless is not universal: the regulator must match the injector setup, and any factory low-pressure warning switch must still work. If the instructions do not show the FD3S return and sender connections, request a diagram before proceeding.

For most builds, the least invasive choice is a complete module that matches the manual and retains the original sender. Compare the package, including seals, electrical pieces and hardware, rather than price alone.

Fit the pump and preserve the tank module

Once the car is safe, drain the tank into approved containers and remove it or the module as the manual directs. Support the tank, label supply, return and vapour lines, and never pull on EFI hoses. Keep the filler neck and vent sealed.

Remove the sender without twisting its float arm. Compare orientation, shaft length and gasket with the replacement, and inspect the basket for corrosion. Retain a known-good float and level sender unless the kit explicitly replaces it.

Fit the pump to its instructions, including orientation and priming. Many pumps must be flooded with petrol before first operation; others must never run dry. Use the specified seal, seat the module squarely and tighten fasteners to the manual figure rather than crushing plastic.

Connect the outlet with clean compatible hose and secure it away from chafing points. Reinstall the tank, straps and lines without kinks or strain, restore the filler cap and vent, and clear spilled petrol before reconnecting the battery. Inspect the bay and underbody for leaks.

Wire the pump for protected operation

Give the pump a protected power path. Route a suitably sized fused feed through the intended fuel-pump relay or controller, keep ECU outputs as low-current triggers, and place protection near the supply. Size cables, connectors and fuses for peak draw, not quiet running current.

Use a clean chassis ground, sound crimps and a weatherproof connector. Verify polarity before energising the pump, secure the loom away from exhaust heat, and retain any factory low-pressure warning switch. Fit and label every added resistor or relay as the wiring diagram requires.

Engine management must agree with the fuel system because pressure, injector flow and pulse width affect one another. The PowerFC tuning guide covers the software side, but begin with conservative injector values, confirm rail pressure and use wideband data where fitted. A 13B and 20B with the same pump can still require different calibration.

Pressure-test, tune and return the car to service

Prime the system as specified, then watch for steady pump noise and immediate fuel pressure. A fast rise at the pump does not prove correct pressure; use a suitable gauge at the rail and compare it with the service-manual range, not the seller’s maximum.

After the first warm cycle, inspect the module, hoses, fittings and connectors. Confirm any low-pressure warning switch operates and the relay does not cycle with the engine off. Correct heat, noise or pressure irregularity before tuning.

Road-test in stages, from light traffic to the loads the car actually encounters. A hot day in Brisbane or a climb from Melbourne into regional Victoria can reveal weaknesses that a stationary test misses. Watch for hesitation, misfire, overheating or a fuel smell, then repeat the pressure check.

Before the first drive, use the TurboRX7 technical library to verify the pump specification, FD3S diagrams and tuning guidance against the fitted hardware. Record pressure, current draw and injector settings, keep the warning circuit operational, and drive only after every leak, wiring and pressure check passes.