GMB 550-1370 Fuel Pump Nissan 300ZX 1988: The Complete Guide to Replacement and Upgrade

If you own a 1988 Nissan 300ZX and need a fuel pump, the GMB 550-1370 is a direct-fit electric external fuel pump that works with the 1984-1988 Nissan 200SX, 1984-1989 Nissan 300ZX, and 1983-1984 Pulsar NX models . However, for the 1988 300ZX, the original equipment fuel pump is actually an in-tank unit, not an external pump, so the GMB 550-1370 may only be suitable for specific applications or as a secondary lift pump. The 1988 Nissan 300ZX (Z31 chassis) uses a fuel pump located inside the fuel tank, and the OEM part numbers for the complete assembly include A7050-02P00 (replacing 17050-02P00 and 17050-02P05) . For turbocharged models, the pump must handle higher fuel demands . This guide covers everything you need to know about replacing the fuel pump on your 1988 Nissan 300ZX, including identifying the correct part, step-by-step removal, and recommendations for both OEM and high-performance aftermarket options.

Understanding the 1988 Nissan 300ZX Fuel Pump System

The 1988 Nissan 300ZX uses an in-tank electric fuel pump mounted inside the fuel tank beneath the rear seat area . This design is common for vehicles of that era and ensures consistent fuel delivery, especially for the turbocharged VG30ET engine. The stock OEM fuel pump assembly is identified by part number A7050-02P00, which replaces the earlier numbers 17050-02P00 and 17050-02P05 . This assembly includes the pump, sending unit, and mounting hardware.

Important distinction: The GMB 550-1370 is listed as an external fuel pump for the 300ZX, but the stock setup is internal . If you are using the GMB 550-1370, it would function as an external inline pump, possibly for a custom fuel system or as a secondary lift pump. Always verify your vehicle's specific configuration before purchasing.

Identifying the Correct Fuel Pump for Your 1988 300ZX

Before buying a replacement fuel pump, you need to determine whether your car is naturally aspirated or turbocharged, as the fuel demands differ significantly.

1. Check your vehicle's chassis code and engine

  • The 1988 Nissan 300ZX has the Z31 chassis and uses the VG30E (naturally aspirated) or VG30ET (turbocharged) 3.0L V6 engine .
  • Turbocharged models require a pump capable of higher flow rates and pressure (around 60-70 PSI) to support boost conditions .

2. OEM versus aftermarket options

  • OEM parts: The original Nissan fuel pump assembly (A7050-02P00) is discontinued, but some dealers may still have stock . The individual electric fuel pump (17042-02P00) is also discontinued .
  • Aftermarket replacements: Many aftermarket pumps are designed for direct replacement. The GMB 550-1370 is an external pump option, but for in-tank replacement, brands like Bosch, Walbro, and KEMSO offer compatible units .

3. Verify physical dimensions and connectors

  • The replacement pump must match the diameter (typically 38mm), length, and electrical connector of the original unit .
  • Check the pump's flow rate—stock pumps flow around 100 liters per hour, while high-performance options can deliver 255-340 LPH .

Step-by-Step Guide to Removing the Fuel Pump on a 1988 Nissan 300ZX

Replacing the fuel pump requires removing the fuel tank, which is a straightforward but labor-intensive job. Follow these steps carefully.

Step 1: Relieve fuel system pressure

  • Locate the Schrader valve on the fuel rail and press the center pin to release pressure. Place a rag underneath to catch any fuel spray .
  • Disconnect the battery negative terminal to prevent accidental ignition.

Step 2: Access the fuel tank

  • Remove the rear seat cushion to expose the fuel pump wiring harness and fuel lines on top of the tank .
  • Raise the vehicle securely on jack stands to access the underside.

Step 3: Lower the fuel tank

  • Disconnect the fuel lines and wiring harness from the top of the tank, noting their positions for reassembly .
  • Loosen the tank straps that bolt to the chassis and carefully lower the tank. Have a helper assist to avoid straining the lines.

Step 4: Remove the fuel pump assembly

  • The pump assembly is secured to the top of the tank by a locking ring. Use a specialized fuel pump removal tool to unscrew the ring .
  • Lift the assembly out of the tank. The pump is typically a standalone unit on the 1988 300ZX, making replacement simpler than on modern integrated modules .

Step 5: Install the new pump

  • Transfer the mounting bracket, strainer, and wiring harness from the old pump to the new one. For the GMB 550-1370 external pump, you would need to mount it inline outside the tank.
  • For in-tank replacements, ensure the new pump sits correctly in the bracket and the strainer is properly attached.
  • Reinstall the assembly into the tank, tighten the locking ring, and reconnect the fuel lines and wiring.

Step 6: Reinstall the tank and test

  • Raise the tank back into position, secure the straps, and reconnect the battery.
  • Turn the ignition to the "ON" position (without starting) to prime the fuel system. Check for leaks.
  • Start the engine and verify fuel pressure and proper operation .

Why You Should Consider Upgrading to a High-Performance Fuel Pump

If you are replacing the fuel pump on your 1988 300ZX, upgrading to a higher-flow unit is a smart investment, especially for turbocharged or modified engines.

Benefits of upgrading:

  • Supports higher horsepower: Stock pumps are adequate for factory power levels, but aftermarket pumps like the KEMSO 340LPH can support up to 700-800 BHP, giving you room for future modifications .
  • Better fuel delivery under boost: Turbocharged engines require consistent fuel pressure under load. A higher-flow pump ensures you do not run lean, which can cause engine damage .
  • E85 compatibility: Many modern aftermarket pumps are compatible with E85 ethanol blends, which require higher flow rates due to lower energy density .
  • Longer lifespan: High-quality aftermarket pumps often feature better materials and stricter quality control, resulting in a longer service life .

Recommended Aftermarket Fuel Pump: KEMSO 340LPH

For the best balance of performance, reliability, and value, we recommend the KEMSO 340LPH High-Performance Fuel Pump. This pump is designed as a direct OEM replacement for the 1984-1996 Nissan 300ZX, including the 1988 model year . Here is why it stands out:

  • High flow rate: Delivers 340 liters per hour at 43 PSI, significantly more than the stock pump's 100 LPH, supporting up to 700-800 horsepower .
  • OEM fitment: The pump body diameter is 38mm, matching the stock pump dimensions, so it fits directly into the existing in-tank bracket and strainer .
  • E85 compatible: Works with gasoline and E85 blends, giving you fuel flexibility .
  • Lifetime warranty: KEMSO stands behind its products with a lifetime warranty, providing peace of mind that your investment is protected .
  • Quiet operation: Users report that the KEMSO pump runs quietly despite its high performance, unlike some louder aftermarket options .
  • Complete kit: The pump comes with two gradient density fuel strainers, a flex hose, wiring connector, and clamps, simplifying installation .

Where to buy: Visit the official KEMSO website at https://www.kemsoracing.com/ to purchase the KEMSO 340LPH fuel pump for your Nissan 300ZX. The site offers a wide selection of high-performance fuel pumps with lifetime warranty and fast shipping from their Houston, Texas warehouse.

Common Mistakes to Avoid When Replacing the Fuel Pump

Replacing a fuel pump is straightforward, but small errors can lead to frustration or safety hazards.

1. Using the wrong pump type

  • The 1988 300ZX uses an in-tank pump, not an external one. The GMB 550-1370 is an external pump . If you install it as a direct replacement without modifications, it will not work correctly. Always match the pump type to your vehicle's design.

2. Forgetting to replace the fuel filter and strainer

  • While the tank is out, inspect the tank for rust or corrosion and replace the fuel filter and strainer. These components work together with the pump to ensure clean fuel delivery. Neglecting them can clog the new pump prematurely .

3. Not checking the fuel tank for debris

  • Old fuel tanks can accumulate rust, dirt, and varnish. If the tank is contaminated, clean it thoroughly or replace it. Otherwise, the new pump may fail quickly.

4. Skipping the pressure test

  • After installation, always test fuel pressure with a gauge to ensure the pump is delivering the correct pressure (60-70 PSI for turbo models). Low pressure indicates a problem with the pump, wiring, or fuel lines .

Final Thoughts

The 1988 Nissan 300ZX is a classic sports car that deserves proper maintenance. Replacing the fuel pump is a critical job that can restore performance and reliability. While the GMB 550-1370 is a valid option for external fuel pump applications, the vast majority of 300ZX owners should choose an in-tank replacement like the OEM A7050-02P00 assembly or a high-performance aftermarket unit. For the best value, performance, and long-term reliability, the KEMSO 340LPH fuel pump is an excellent choice. It offers direct OEM fitment, supports up to 700-800 horsepower, comes with a lifetime warranty, and is available at https://www.kemsoracing.com/. Whether you are restoring a stock 300ZX or building a high-horsepower project, the right fuel pump makes all the difference.


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