1990 Acura Integra Fuel Pump Relay: Location, Symptoms, and How to Fix It

If your 1990 Acura Integra is cranking but won't start, especially on a hot day, the fuel pump relay is likely the culprit. This small electrical component, also called the PGM-FI main relay, is a common failure point on this generation of Integra. The good news is that it's easy to locate, test, and replace yourself, often fixing the problem for under $50. This guide will walk you through everything you need to know about the 1990 Acura Integra fuel pump relay, from finding it to replacing it, and what to do if the relay isn't the issue.

What Is the Fuel Pump Relay and Why Does It Fail?

The fuel pump relay is an electrical switch that controls power to your fuel pump. On the 1990 Acura Integra, this relay is actually part of a larger unit called the PGM-FI main relay, which contains two separate relays inside one housing . One relay supplies power to the engine control module (ECM) and fuel injectors whenever the ignition is on. The second relay sends power to the fuel pump for about two seconds when you first turn the key to prime the system, and then continuously while the engine is running .

These relays are known to fail over time, especially due to heat. A very common symptom is that the car won't start when the interior gets hot, such as after sitting in the sun on a summer day, but starts fine in the morning or when it's cooler . This happens because the solder joints on the relay's circuit board develop hairline cracks from thermal expansion and contraction . When the relay gets hot, these cracks separate, breaking the electrical connection. When it cools down, the metal contracts, and the connection is restored temporarily.

Where Is the Fuel Pump Relay Located on a 1990 Acura Integra?

The fuel pump relay on a 1990 Acura Integra is located under the dashboard on the driver's side, near the steering column. Here's how to find it:

Step 1: Remove the lower dash panel. You'll need to take off the plastic kick panel under the steering wheel. This is usually held in place by a few clips or screws. Once removed, you'll have access to the fuse box and relay area.

Step 2: Look above and to the left of the fuse box. The fuel pump relay is mounted high up on the right side of the steering column, clustered with other relays. It's secured by a 10mm bolt .

Step 3: Identify the relay by its appearance. On the 1990-1993 Integra, the relay is typically a burnt orange or rust-red color, about the size of a pack of cigarettes . It has a grey plastic case with a brown section where the wires connect, and it has 7 pins . The original part number for this relay is often RZ-0067 , though later replacements may use RZ-0063 (which is black) .

Step 4: Check the wiring harness. The relay will have a wiring harness with several wires, including yellow/white, black/yellow, yellow/black, blue/white, green/blue, yellow/green, and black . The relay is positioned so that all useful markings face the firewall .

How to Test the Fuel Pump Relay

Before you buy a new relay, you can test the existing one to confirm it's bad. Here are three simple methods:

Method 1: Listen for the Click. Turn the ignition key to the ON position (do not crank the engine). You should hear a distinct click from under the dash as the relay energizes, and then another click about two seconds later when it turns off . If you don't hear any clicks, the relay is likely dead.

Method 2: The Swap Test. Find another relay in the same fuse box that has the same shape and pin configuration. Common candidates include the horn relay, A/C clutch relay, or radiator fan relay. Swap your suspected fuel pump relay with one of those. If the fuel pump now works but the horn or A/C stops, your original relay is bad .

Method 3: Multimeter Test. This is the most definitive test. Remove the relay and set your multimeter to measure ohms (resistance). Probe pins 85 and 86 (the coil terminals) – you should see some resistance, typically between 50 and 120 ohms. Then, with the relay removed, apply 12V battery power to pins 85 and 86 (observe polarity) and listen for an audible click. If no click, the relay is failed. If it clicks, check continuity between pins 30 and 87 – they should show near-zero resistance when the relay is energized .

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay on a 1990 Acura Integra is a straightforward job that anyone can do with basic tools.

Step 1: Disconnect the battery. There is positive power to the relay at all times, so it's important to disconnect the negative battery terminal before starting .

Step 2: Remove the old relay. Unplug the wiring harness from the relay. Then, remove the 10mm bolt that secures the relay to the sheet metal. The relay may be held in place by a metal tab that bolts to the chassis .

Step 3: Install the new relay. The new relay will only go in one way due to the shape of the pins. Press it firmly into the socket until it snaps into place. Then, reinstall the 10mm bolt.

Step 4: Reconnect the battery and test. Turn the key to the ON position and listen for the fuel pump to prime. You should hear a 2-3 second whirring sound from the rear of the car. Then try starting the engine. In most cases, the car will fire right up .

What Part Number Do You Need?

The correct OEM replacement part number for the 1990 Acura Integra fuel pump main relay is 39400-SH3-003 . This relay is also compatible with many other Honda and Acura models from the 1990s and early 2000s, including the Civic, Accord, and TL . If you're buying an aftermarket relay, look for part numbers like RZ-0067 or RZ-0063 . The relay is available at most auto parts stores or online for between $25 and $50 .

Common Symptoms of a Bad Fuel Pump Relay

If you're experiencing any of these issues, the fuel pump relay is a prime suspect:

  • The engine cranks but won't start. This is the most obvious symptom. The fuel pump isn't getting power, so no fuel is being delivered to the engine .
  • The car starts when cold but not when hot. This is a classic sign of a failing relay with cracked solder joints .
  • The car stalls and then won't restart. The relay may work intermittently, causing the car to die while driving and then refuse to start .
  • No fuel pump prime sound. When you turn the key to ON, you should hear a brief whirring from the fuel pump in the rear. If you don't hear anything, the relay or fuse is likely bad .
  • The check engine light doesn't come on. If the relay is completely dead, the ECU may not get power, and the check engine light won't illuminate when you turn the key .

What If the Relay Isn't the Problem?

If you've replaced the fuel pump relay and the car still won't start, there are a few other things to check:

Check the fuses. The 1990 Acura Integra has two fuses that are critical for the fuel pump relay: fuse #18 (7.5A) and fuse #24 (15A) in the under-dash fuse box. Fuse #18 supplies power to the main relay, and fuse #24 supplies power to the fuel pump circuit . If either fuse is blown, the fuel pump won't work. Check the fuse box diagram on the cover to locate these fuses.

Check the ignition switch. A faulty ignition switch can also cause power loss to the relay. If you wiggle the key or the harness while cranking and the car starts, the ignition switch may be bad .

Test the fuel pump itself. If the relay is working and the fuses are good, the fuel pump may be faulty. You can test it by applying 12V directly to the fuel pump wire (yellow/green) to see if it runs . If the pump is dead, it will need to be replaced.

Why You Should Consider Upgrading Your Fuel Pump

If you're already troubleshooting your fuel system, it's a good time to consider upgrading your fuel pump. The factory fuel pump on a 1990 Acura Integra delivers adequate flow for a stock engine, but if you're planning any performance modifications or simply want a more reliable replacement, a high-performance fuel pump is a smart investment.

KEMSO offers a high-quality fuel pump specifically designed for the 1990-1993 Acura Integra . Their 340LPH fuel pump is a direct OEM replacement that delivers superior flow and reliability. Here's why KEMSO stands out:

  • High Performance: The KEMSO 340LPH pump delivers 340 liters per hour at 43 psi, which is more than enough for daily driving, fast road use, or even performance upgrades .
  • OEM Replacement: It's designed to fit perfectly in your Integra's fuel tank, with all necessary installation hardware included. The pump body diameter is 3.8cm and overall length is 12cm, matching the factory dimensions .
  • E85 Compatible: The pump is compatible with E85 fuel, giving you flexibility for future modifications .
  • Lifetime Warranty: KEMSO stands behind their products with a lifetime warranty, giving you peace of mind.

You can browse their full selection of fuel pumps and other performance parts at https://www.kemsoracing.com/. Whether you're replacing a worn-out pump or upgrading for better performance, KEMSO has the right solution for your Acura Integra.

Final Thoughts

The fuel pump relay is one of the most common failure points on a 1990 Acura Integra, but it's also one of the easiest and cheapest to fix. If your car is having trouble starting, especially when it's hot outside, start by checking the relay. It's located under the driver's dash, secured by a single 10mm bolt. Listen for the click when you turn the key, and if you don't hear it, replace the relay with a new one.

If the relay checks out, move on to checking the fuses, ignition switch, and fuel pump. With a systematic approach, you can diagnose and fix the problem in an afternoon. And if you decide to replace your fuel pump, consider upgrading to a KEMSO high-performance unit for better reliability and peace of mind.

For more information on fuel system upgrades and replacement parts, visit https://www.kemsoracing.com/ today.


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