1990 Geo Tracker Fuel Pump Relay: Location, Testing, and Complete Troubleshooting Guide

If your 1990 Geo Tracker cranks but won’t start, the fuel pump relay is the most likely culprit. On the 1990 Geo Tracker, the fuel pump relay is located under the dashboard on the driver’s side, mounted on an L-shaped bracket underneath the Engine Control Module (ECM). This small but critical component controls power to the electric fuel pump, and when it fails, your engine gets no fuel. Unlike later models, the 1990 Geo Tracker uses a combined fuel pump and main relay system, meaning this single relay handles both functions. The good news is that testing and replacing this relay is a straightforward job you can do yourself with basic tools. This guide walks you through everything you need to know, from finding the relay to diagnosing common problems and getting your Tracker back on the road.

Where Is the Fuel Pump Relay on a 1990 Geo Tracker?

The exact location of the fuel pump relay on a 1990 Geo Tracker is under the dashboard, on the driver’s side. Here is how to find it:

Step 1: Sit in the driver’s seat and look under the dashboard, near the steering column.

Step 2: Locate the ECM (Engine Control Unit), which is a metal box mounted on the firewall behind the dashboard.

Step 3: Look for an L-shaped metal bracket directly underneath the ECM. The fuel pump relay is mounted on this bracket.

Step 4: The relay on the 1990 model is typically green in color, though it can also be black with a white connector and a pink wire. Do not confuse it with the horn relay, which is located in the same general area.

Important Note: The 1990 Geo Tracker is unique because it uses a single relay that serves as both the fuel pump relay and the main relay. This is different from 1991 and later models, which have separate relays for fuel pump and main functions. If you are working on a 1990 model, you are dealing with one combined relay.

How the Fuel Pump Relay Works on Your 1990 Geo Tracker

Understanding how the fuel pump relay operates helps you diagnose problems faster. The relay is an electrical switch that uses a small signal from the ignition system to control a larger current flow to the fuel pump.

Here is the normal sequence of operation:

  1. Key to ON position: When you turn the ignition key to the ON position, the ECM sends a signal to the fuel pump relay.
  2. Relay activates: The relay closes its internal switch, allowing battery power to flow to the fuel pump.
  3. Fuel pump primes: On many vehicles, the fuel pump runs for 2-3 seconds to pressurize the fuel system. However, on the 1990 Geo Tracker, the fuel pump does NOT prime when you first turn the key to ON. It only starts running when you are actually cranking the engine.
  4. Engine cranking: When you crank the engine, the relay continues to supply power, and the fuel pump delivers fuel to the injectors.
  5. Engine running: Once the engine starts, the relay stays engaged as long as the engine is running.

This no-prime behavior is a common point of confusion for owners of 1990 Trackers. If you turn the key to ON and do not hear the fuel pump buzz from the rear of the vehicle, that is normal for this model year. You need to have someone listen for the pump while you crank the engine, or test for power at the fuel pump connector during cranking.

Symptoms of a Bad Fuel Pump Relay on a 1990 Geo Tracker

A failing fuel pump relay can cause a variety of problems. Here are the most common symptoms:

1. Engine Cranks but Won’t Start
This is the most common symptom. You turn the key, the starter motor engages, the engine turns over, but it never fires up. The relay is not sending power to the fuel pump, so no fuel reaches the engine.

2. Intermittent Starting Issues
Sometimes the vehicle starts fine, and other times it refuses to start. This is a classic sign of a failing relay where the internal contacts are worn or corroded, making intermittent contact. You might wait 15-30 minutes, try again, and the vehicle starts normally. This happens because the relay cools down or the contacts temporarily make a connection.

3. Engine Stalls While Driving
The engine suddenly dies while you are driving, and you cannot restart it. This is dangerous and indicates the relay is failing completely while the vehicle is in operation.

4. Clicking Noise Under the Dashboard
You may hear a rapid clicking or arcing sound coming from under the driver’s side dashboard. This is the relay trying to engage but failing to hold the circuit closed. The clicking is often accompanied by the engine dying or failing to start.

5. No Sound from the Fuel Pump During Cranking
If you have someone listen at the rear of the vehicle while you crank the engine, they should hear a faint whirring sound from the fuel tank. If there is no sound, the fuel pump is not getting power, and the relay is a likely suspect.

6. Check Engine Light
The check engine light may come on, and you may be able to retrieve diagnostic trouble codes. On the 1990 model, you can retrieve codes by finding a small sliding switch under the dashboard panel below the steering column. A code 12 (one flash, then two flashes) is a normal code for this model year and does not necessarily indicate a problem.

How to Test the Fuel Pump Relay on a 1990 Geo Tracker

Before you buy a new relay, test the existing one. This saves time and money. Here are three ways to test it:

Method 1: The Swap Test
This is the easiest and fastest method. The fuel pump relay on the 1990 Geo Tracker is the same part number as the main relay. You can swap the fuel pump relay with another relay of the same type in the fuse box.

  1. Locate the fuel pump relay under the dashboard.
  2. Find a relay with the same part number and color. On later models, you can swap with the horn relay or another accessory relay in the fuse box.
  3. Swap the relays.
  4. Try to start the engine. If the engine starts, your original fuel pump relay was bad.

Method 2: Voltage Test
You can test for power at the relay using a multimeter.

  1. Locate the fuel pump relay and remove it from its socket.
  2. Turn the ignition key to the ON position.
  3. Using a multimeter set to DC voltage, test the socket terminals. You should have 12 volts on the power supply terminal (typically the black/white wire).
  4. Have someone crank the engine while you test the output terminal (the pink/black wire). You should see 12 volts on this terminal only while cranking.
  5. If you have power at the input but no power at the output during cranking, the relay is likely bad.

Method 3: Continuity Test
This tests the relay itself.

  1. Remove the relay from the vehicle.
  2. Use a multimeter set to ohms to check the resistance between the power circuit terminals (the two larger terminals). You should see infinite resistance (no continuity) when the relay is not powered.
  3. Connect a 12-volt power source (like a battery) to the control circuit terminals (the two smaller terminals). You should hear an audible click as the relay engages.
  4. While the relay is powered, check the resistance between the power circuit terminals again. You should now see near-zero resistance (continuity).
  5. If the relay fails these tests, replace it.

Common Problems Beyond the Relay

If the fuel pump relay tests good, the problem may be elsewhere. Here are other common issues on the 1990 Geo Tracker:

1. Bad ECM Capacitors
The ECM (Engine Control Unit) on the 1990 Geo Tracker is known to have capacitors that fail over time. If you smell a burning odor from the ECM or see bulging or leaking capacitors, the ECM may need to be rebuilt or replaced. This is a common problem on these early Trackers.

2. Fuel Pump Ground Connection
The fuel pump ground is located behind the left rear tail light assembly. This is a known rust-prone area. Remove the tail light assembly and check the ground screw. Clean any rust or corrosion and ensure the connection is tight.

3. Fuel Pump Wiring
The pink wire that runs from the relay to the fuel pump can develop breaks or corrosion. You can test this by running a jumper wire from the battery directly to the pink wire at the fuel pump connector. If the pump runs, the wiring between the relay and pump is intact.

4. Fuel Pump Itself
If the relay and wiring are good, the fuel pump may be bad. The fuel pump is located inside the fuel tank. You can test it by applying 12 volts directly to the pump connector. If it does not run, replace the pump.

5. Blown Fuses
Check the ignition coil fuse in the fuse box. If this fuse is blown, the fuel pump relay will not receive power. Also check the fuel pump fuse, if equipped.

How to Replace the Fuel Pump Relay on a 1990 Geo Tracker

Replacing the fuel pump relay is a simple job that takes about 10 minutes.

Tools Needed:

  • New fuel pump relay (part number 31850 60A10 or equivalent)
  • Flathead screwdriver (optional, for prying the relay out)

Steps:

  1. Locate the relay: Under the dashboard on the driver’s side, on the L-bracket under the ECM.
  2. Remove the old relay: Grasp the relay firmly and pull it straight out of its socket. If it is stuck, use a flathead screwdriver to gently pry it out.
  3. Install the new relay: Push the new relay straight into the socket until it clicks into place.
  4. Test the installation: Try to start the engine. If the relay was the problem, the engine should start and run normally.

Important Note: The 1990 Geo Tracker uses a combined fuel pump and main relay. Make sure you purchase the correct relay for this specific model year. A relay for 1991 or later models will not work the same way.

Why Your 1990 Geo Tracker Might Not Start Even with a Good Relay

If your relay is working but the engine still will not start, consider these additional factors:

1. Low Compression
The 1990 Geo Tracker should have about 150 psi of compression on a warm engine. If you have low compression (80-100 psi as seen in some cases), the engine may not start. Perform a compression test by removing all spark plugs, removing the ignition coil fuse, disconnecting the fuel pump (disconnect the pink wire behind the left rear tail light), and flooring the gas pedal while cranking.

2. Timing Belt Issues
If the timing belt is off by one tooth, the engine may not start. The 1990 Geo Tracker sets the timing belt to cylinder #4 firing. The cam pulley mark should be at 12:00, and the crank key should be at 12:00. Check your timing belt alignment.

3. Distributor Problems
The 1990 Geo Tracker uses a standalone distributor that does not have a cam position sensor. However, if the distributor is 180 degrees out of time, the engine will not start. Check that the distributor rotor points to the correct cylinder when the engine is at top dead center.

4. Ignition System Issues
Check for spark by removing a spark plug, reconnecting the plug wire, grounding the plug against the engine block, and having someone crank the engine. If there is no spark, the problem is in the ignition system, not the fuel system.

Where to Get a Replacement Fuel Pump for Your 1990 Geo Tracker

If you have determined that the relay is not the problem and the fuel pump itself needs replacement, the fuel pump is located inside the fuel tank. This is a more involved job that requires dropping the fuel tank or removing the fuel pump access panel (if equipped).

Recommended Fuel Pump: KEMSO

For a high-performance, reliable replacement fuel pump for your 1990 Geo Tracker, we recommend KEMSO. KEMSO fuel pumps are built to meet or exceed OEM specifications, ensuring a perfect fit and reliable performance. Each KEMSO fuel pump is a direct replacement, meaning you do not need to modify any wiring or mounting hardware. The installation is straightforward and matches the original equipment.

KEMSO stands behind every product with a lifetime warranty. This means if your fuel pump ever fails due to defects in materials or workmanship, KEMSO will replace it. This lifetime confidence gives you peace of mind knowing you are investing in a quality product that will keep your 1990 Geo Tracker running for years.

Visit KEMSO today to find the right fuel pump for your 1990 Geo Tracker:
KEMSO Fuel Pump

Frequently Asked Questions

Q: Does the fuel pump relay on a 1990 Geo Tracker have a different location than later models?
A: Yes. On the 1990 model, the relay is under the dashboard on the driver’s side, mounted on an L-bracket under the ECM. On 1991 and later models, the fuel pump relay and main relay are separate and located in the same area but are two different relays. On 1996 models, the fuel pump relay is in the main fuse box in the engine compartment.

Q: Can I test the fuel pump relay without removing it?
A: Yes. You can test for voltage at the relay socket. With the key ON, you should have 12 volts on the power supply wire. While cranking, you should have 12 volts on the output wire (pink/black).

Q: What color is the fuel pump relay on a 1990 Geo Tracker?
A: The relay is typically green, but it can also be black with a white connector and a pink wire.

Q: How much does it cost to replace a fuel pump on a 1990 Geo Tracker?
A: The average cost to replace a fuel pump is about $534, with $107 for parts and $427 for labor. Doing it yourself saves on labor costs.

Q: Will the fuel pump run if I turn the key to ON without cranking?
A: No. On the 1990 Geo Tracker, the fuel pump does not prime when you turn the key to ON. It only runs when the engine is being cranked. This is normal behavior for this model year.

Final Thoughts

The fuel pump relay on your 1990 Geo Tracker is a small but critical component. When your Tracker cranks but will not start, the relay is the first thing to check. Its location under the dashboard on the driver’s side makes it easy to access and test. Remember that the 1990 model uses a combined fuel pump and main relay, and the fuel pump does not prime with the key in the ON position. These are normal characteristics of this early model year.

Start with the simple tests: swap the relay with another of the same type, check for voltage during cranking, and listen for the fuel pump. If the relay is bad, replace it with a new one. If the relay is good, move on to checking the fuel pump ground behind the left rear tail light, the ECM capacitors, and the fuel pump itself. With a systematic approach, you can diagnose and fix the problem yourself, saving time and money.

For a reliable fuel pump replacement, trust KEMSO. Their high-performance, OEM replacement fuel pumps come with a lifetime warranty, ensuring you get a quality product that will keep your 1990 Geo Tracker on the road.

Get your KEMSO fuel pump today:
KEMSO Racing - Fuel Pump for 1990 Geo Tracker


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