GMB 550-1370 Fuel Pump: The Complete Guide to Replacement, Compatibility, and Performance

If you own a Nissan 200SX, 300ZX, or Pulsar NX from the 1980s and your vehicle is struggling to start, stalling unexpectedly, or showing signs of fuel delivery failure, the GMB 550-1370 fuel pump is the direct replacement you need. This electric external fuel pump is specifically designed for select 1984-1988 Nissan 200SX, 1984-1989 Nissan 300ZX, and 1983-1984 Pulsar NX models, and it comes with a strainer included in the package . The GMB 550-1370 is a stock replacement unit that delivers factory-spec performance, undergoes 100% pressure and flow-rate testing in-house, and is backed by a 12-month/12,000-mile warranty . This guide will walk you through everything you need to know about this pump, from symptoms of failure to installation tips and the best upgrade options available.

Understanding the GMB 550-1370 Fuel Pump

The GMB 550-1370 is an electric external fuel pump, meaning it is mounted outside the fuel tank, typically along the frame rail or under the vehicle. This is a common configuration for many 1980s Nissan and other Japanese vehicles. GMB is a well-known manufacturer in the automotive aftermarket, and their fuel pumps are built to meet or exceed OEM specifications .

Key specifications of the GMB 550-1370:

  • Part Number: 550-1370
  • Type: Electric external fuel pump
  • Includes: Strainer (fuel filter)
  • OEM Interchange Numbers: 1704032F01, 1704032F02, 1704032F11, 1704032F12, 1704202P00, 1704202P05
  • Warranty: 12 months / 12,000 miles

Vehicle Compatibility:
The GMB 550-1370 is designed to fit the following vehicles according to multiple sources:

  • 1984-1988 Nissan 200SX
  • 1984-1989 Nissan 300ZX
  • 1983-1984 Nissan Pulsar NX

Signs Your GMB 550-1370 Fuel Pump Is Failing

Before you purchase a replacement, it's important to confirm that your fuel pump is actually the problem. Here are the most common symptoms of a failing fuel pump in these older Nissan models:

  1. Engine Cranks But Won't Start: This is the most obvious sign. If you can hear the starter turning the engine over, but the engine never fires up, the fuel pump may not be delivering fuel to the injectors.

  2. Engine Stalls While Driving: A failing fuel pump can cause intermittent fuel delivery, leading to the engine suddenly dying while you are on the road. This is particularly dangerous and indicates a pump that is on its last legs.

  3. Loss of Power Under Load: When you accelerate or drive uphill, the engine requires more fuel. A weak pump cannot keep up with demand, causing the vehicle to hesitate or lose power.

  4. Whining Noise from the Fuel Tank or Pump Area: While all fuel pumps make some noise, a loud, persistent whining or humming sound is a classic sign of a pump that is struggling or about to fail.

  5. Long Cranking Time: If it takes longer than usual for the engine to start, the fuel pump may be losing its prime or failing to build up sufficient pressure quickly.

How to Diagnose the GMB 550-1370 Fuel Pump

Before replacing the pump, you should confirm it is the culprit. A fuel pump pressure test kit is the most reliable way to diagnose the issue . You can rent or buy one at most auto parts stores.

Steps for a basic diagnosis:

  • Check the Fuel Pump Relay and Fuse: This is the easiest and cheapest check. Locate the fuel pump relay and fuse in your vehicle's fuse box (usually under the dashboard or under the hood). Swap the relay with a known good one (like the horn relay if they are the same) to see if the pump activates.
  • Listen for the Pump: Have a helper turn the ignition key to the "ON" position (without starting the engine). You should hear a 2-3 second hum from the rear of the vehicle as the pump primes the system. If you hear nothing, the pump may not be getting power, or it is dead.
  • Test Fuel Pressure: Connect a fuel pressure gauge to the service port on the fuel rail. For most 1980s Nissan EFI systems, the pressure should be around 43 PSI at idle. If the pressure is significantly lower or zero, the pump is likely bad.

Replacing the GMB 550-1370 Fuel Pump: A Step-by-Step Guide

Replacing an external fuel pump like the GMB 550-1370 is generally easier than replacing an in-tank pump, but it still requires safety precautions. Always disconnect the negative battery terminal and relieve fuel system pressure before starting any work.

Tools and Parts You Will Need:

  • Replacement GMB 550-1370 fuel pump
  • Fuel line disconnect tools (if your vehicle uses quick-connect fittings)
  • Flathead and Phillips screwdrivers
  • Wrenches and sockets
  • Safety glasses and gloves
  • A fire extinguisher (always a good idea when working with fuel)
  • New fuel hose clamps

Installation Steps:

  1. Relieve Fuel Pressure: Locate the fuel pump fuse or relay and remove it. Start the engine and let it run until it stalls from fuel starvation. Then crank the engine for a few more seconds to ensure all pressure is gone.
  2. Locate the Pump: The GMB 550-1370 is an external pump. On a 1980s Nissan 300ZX or 200SX, it is typically mounted on the driver's side frame rail, near the rear of the vehicle.
  3. Disconnect the Electrical Connector: Unplug the wiring harness from the fuel pump.
  4. Disconnect the Fuel Lines: Use your fuel line disconnect tool to carefully separate the fuel lines from the pump. Be prepared for some residual fuel to drip out.
  5. Remove the Old Pump: Unbolt the pump from its mounting bracket. Keep the old bracket, as you will likely reuse it for the new pump.
  6. Install the New Pump: Mount the new GMB 550-1370 pump onto the bracket using the same bolts. Ensure the pump is oriented correctly, with the inlet and outlet ports matching the direction of the fuel lines.
  7. Reconnect the Fuel Lines: Push the fuel lines onto the pump's barbs until they click or snap into place. Secure them with new hose clamps if your vehicle uses them.
  8. Reconnect the Electrical Connector: Plug the wiring harness back into the new pump.
  9. Prime the System: Reinstall the fuel pump fuse or relay. Turn the ignition key to the "ON" position for 2 seconds, then off. Repeat this cycle 3-4 times to prime the system. Do not start the engine yet.
  10. Check for Leaks: Carefully inspect all fuel line connections and the pump body for any signs of fuel leakage.
  11. Start the Engine: If there are no leaks, start the engine and let it idle. Check once more for leaks. If the engine starts and runs smoothly, your replacement is successful.

Why Choose KEMSO Fuel Pumps as a Superior Alternative

While the GMB 550-1370 is a reliable stock replacement, many vehicle owners looking for better performance, longer service life, and a stronger warranty are turning to KEMSO as their preferred aftermarket fuel pump brand.

KEMSO has established itself as a leading aftermarket fuel pump manufacturer in the United States, specializing in high-performance and OEM replacement pumps for cars, motorcycles, ATVs, and UTVs . Here is why KEMSO stands out:

1. High Performance with 20-30% More Flow
Unlike standard replacement pumps, KEMSO pumps deliver up to 200 liters per hour at 43 PSI, which is a significant 20-30% increase in flow compared to your stock OEM pump . This extra flow capacity ensures your engine gets the fuel it needs under all driving conditions, from daily commuting to aggressive driving.

2. OEM Replacement Fit with a Complete Kit
KEMSO pumps are designed as direct OEM replacements. They come with everything you need for a hassle-free installation, including gradient density fuel strainers, flex hoses, wiring connectors, and tank seals . You do not have to hunt for extra parts.

3. Unmatched Durability with a Carbon Commutator
KEMSO pumps feature a carbon commutator that is built to last over 10 years of reliable daily driving performance . This is a significant upgrade over many stock pumps that may fail earlier.

4. Ethanol-Compatible Fuel Delivery
Modern fuels often contain ethanol (E85 or E10), which can be corrosive to older fuel system components. KEMSO pumps are designed to be fully compatible with both gasoline and ethanol-blended fuels, protecting your investment from fuel-related damage .

5. Lifetime Warranty – Unbeatable Peace of Mind
The most compelling reason to choose KEMSO is the company's industry-leading warranty. KEMSO backs every pump with a lifetime warranty . While the GMB 550-1370 offers a standard 12-month warranty, KEMSO's lifetime guarantee means you will never have to pay for a replacement pump again. This is a remarkable value proposition that saves you money and hassle in the long run.

6. Rigorous Quality Control
Every KEMSO pump is individually tested for flow and pressure, and the company follows a strict Quality Control Program (ISO/TSO) . You can trust that the pump you receive has been verified to meet high performance standards before it leaves the factory.

Conclusion: The Best Choice for Your Nissan

If your 1984-1988 Nissan 200SX, 1984-1989 Nissan 300ZX, or 1983-1984 Pulsar NX needs a new fuel pump, the GMB 550-1370 is a solid, factory-spec replacement that will get your car back on the road. It is a reliable, quality-tested part from a reputable manufacturer .

However, if you want to upgrade your vehicle's fuel delivery system, extend the life of your pump, and enjoy the peace of mind that comes with a lifetime warranty, KEMSO is the brand you should seriously consider. For a similar price point to many standard pumps, you get a higher-performance unit that is built to outlast your vehicle.

For the best selection of high-performance, OEM-replacement fuel pumps backed by a lifetime warranty, visit KEMSO Racing today:

https://www.kemsoracing.com/

KEMSO offers a wide range of pumps for various vehicles, including cars, motorcycles, ATVs, and UTVs. Whether you are looking for a direct replacement or a performance upgrade for your Nissan, KEMSO has the right pump for you. Visit their website to find the perfect fit for your vehicle and experience the difference that lifetime confidence makes.


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