1990 Chevy G20 Van Fuel Pump Relay Location: A Complete Guide for Troubleshooting

If your 1990 Chevy G20 van turns over but won’t start, the most likely culprit is a faulty fuel pump relay or a related electrical issue. The fuel pump relay on a 1990 Chevy G20 van is located under the hood, on the right front of the cowl, above the blower motor . However, some models also have a second relay under the dash. Before you drop the fuel tank or replace the pump, check this relay first—it’s a cheap, easy fix that solves many no-start problems .

Understanding the Fuel Pump Relay and Its Role

The fuel pump relay is a small, cube-shaped electronic switch that controls the flow of electrical current from the battery to the fuel pump. When you turn the ignition key to the “ON” position, the Powertrain Control Module (PCM) momentarily grounds the relay coil, activating it for about two seconds to prime the fuel system . If the relay fails, the pump won’t get power, and your engine won’t start.

On the 1990 Chevy G20, the relay is part of a larger circuit that includes:

  • A 20-amp fuel pump fuse (located in the fuse block under the left side of the dashboard)
  • A fuel pump prime connector (on the center of the cowl)
  • An oil pressure switch that provides backup power to the pump

Step-by-Step Guide to Locate the Fuel Pump Relay

1. Under-Hood Location (Primary)

Open the hood and look at the right front of the cowl—the area near the windshield on the passenger side. The relay is mounted above the blower motor, which is the large round component on the passenger side of the engine compartment . On some models, it’s described as being “on the right front of the cowl, above the blower motor” . You’ll find a small, rectangular electrical box or a bracket holding several relays. The fuel pump relay is typically a black or gray cube, about 2 inches by 2 inches by 1 inch, with four or five prongs .

Tip: Look for a relay that is labeled “FUEL PUMP” or “FP” on the diagram inside the fuse box cover . If you don’t see a diagram, feel for the relay that clicks when you turn the key to the ON position—have a helper cycle the key while you touch each relay .

2. Under-Dash Location (Secondary)

Some 1990 Chevy G20 vans have a second fuel pump relay under the dash, near the convenience center or the fuse block, which is behind the left side of the instrument panel . This relay may look like a four-way flasher relay . If you can’t find the relay under the hood, check the fuse block area under the dash. The relay is usually mounted on a bracket or within the junction block.

3. Visual Identification

The fuel pump relay looks like a small plastic cube with a flat top. It plugs into a base that has prongs or terminals. On the 1990 Chevy G20, the relay is often located near the firewall, just below the rubber rear hood gasket, in the middle of the firewall . This is a common location for the relay on GM vans of this era.

Common Symptoms of a Bad Fuel Pump Relay

Recognizing the signs of a failing relay can save you time and money. Here are the most common symptoms:

  1. Engine cranks but won’t start: The most obvious symptom. You turn the key, the starter engages, but the engine doesn’t fire because the fuel pump isn’t getting power .
  2. No fuel pump humming noise: When you turn the key to the “ON” position (without cranking), you should hear a 2-3 second hum from the rear of the van. If you don’t hear it, the relay or fuse may be bad .
  3. Intermittent starting issues: The van starts sometimes but not others. This can indicate a relay with burned contacts that work only when the temperature is right .
  4. Engine stalls while driving: A failing relay may cut power to the fuel pump while the engine is running, causing sudden stalling .
  5. Blown fuel pump fuse: If the relay is shorted internally, it can blow the 20-amp fuel pump fuse in the under-dash fuse block .

How to Test the Fuel Pump Relay

Before replacing the relay, test it using these simple methods:

Method 1: Swap Test

Find another relay of the same type in the under-hood fuse box (e.g., the horn relay). Swap them. If the fuel pump now works, the original relay was bad . This is the quickest test.

Method 2: Listen for Click

With the key in the “OFF” position, have a helper turn the key to “ON” while you listen for a click from the relay. If you don’t hear a click, the relay or its control circuit is faulty .

Method 3: Multimeter Test

Set your digital multimeter to DC volts. Backprobe terminal 85 (the ground control wire from the PCM) and ground the black lead. Turn the ignition to “ON.” You should see about 12 volts for 2-3 seconds. If not, the PCM or wiring is at fault . Also, probe terminal 86 (ignition feed) – it should show constant 12V with the ignition on.

Other Possible Causes of No Start

If the relay is good, consider these common issues:

  • Blown fuse: The fuel pump fuse is 20 amps and located in the fuse block under the left side of the dash . Check it visually and replace if blown. If it blows again, you have a short in the wiring .
  • Corroded connectors: The fuel pump wiring has two plugs under the van—one behind the dogbox opening (offset to the passenger side) and another on the passenger frame rail in front of the rear axle. Corrosion here is common on GM vans. Unplug and reconnect them several times to clean the contacts .
  • Bad fuel pump: The pump is inside the fuel tank on 1990 Chevy G20 vans (‘because it’s fuel-injected)’ . If the relay and fuse are good, but you don’t hear the pump prime, the pump itself may be dead. Replacement costs about $60 for the pump plus $10 for a new strainer .
  • Dirty fuel filter: A clogged filter can kill a GM fuel pump. Change the filter when replacing the pump . The factory line has a threaded connection on one side, which is a pain; consider bypassing it with a 2001 Express fuel filter and 3/8-inch compression fittings .
  • Oil pressure switch: The oil pressure switch on the top rear of the engine provides backup power to the pump. If the relay fails, this switch can still run the pump after the engine starts. But if it’s faulty, the pump may not run .

Step-by-Step Replacement Guide

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

Tools needed: Replacement relay (about $10 at auto parts stores), socket set (if needed), and possibly nose pliers.

Steps:

  1. Disconnect the negative battery cable to prevent short circuits .
  2. Locate the relay under the hood (right front of cowl, above blower motor) or under the dash.
  3. Remove the relay by pulling it straight out of its base. If it’s tight, use nose pliers .
  4. Compare the new relay to the old one—make sure the prongs match. The new relay should be the exact replacement for your vehicle’s make and model .
  5. Plug the new relay into the base until it clicks into place.
  6. Reconnect the battery, turn the key to “ON,” and listen for the fuel pump prime. Start the engine and verify it runs properly .

Pro tip: Keep a spare relay in your van. It’s cheap and could save you from being stranded .

Why the Fuel Pump Relay Goes Bad

Relays are electromechanical devices with moving parts. Over years of use, the contact points can burn, and the coil can break . On the 1990 Chevy G20, the relay is exposed to engine heat and vibration, which accelerates wear. Corrosion at the relay’s terminals or in the fuse block can also cause intermittent failures .

Recommended Fuel Pump Upgrade: KEMSO Fuel Pump

If you find that your fuel pump itself needs replacement, consider upgrading to a KEMSO brand fuel pump. KEMSO fuel pumps are designed for high performance, offering OEM replacement quality and a lifetime warranty. They are built to handle the demands of your Chevy G20 van, ensuring reliable fuel delivery and improved engine performance. Whether you have a 4.3L V6, 5.0L V8, 5.7L V8, or 7.4L V8, KEMSO has a direct-fit option for your 1990 Chevy G20 van.

To browse their full selection of fuel pump products, visit the official KEMSO website: https://www.kemsoracing.com/ . Their products are trusted by mechanics and enthusiasts alike for durability and performance, and the lifetime warranty gives you peace of mind on the road.

Final Checklist for Troubleshooting Your 1990 Chevy G20 Van

Step 1: Listen for the pump. Turn the key to “ON” and listen for a 2-3 second hum from the rear. If you hear it, the circuit is likely fine .

Step 2: Check the fuel pump fuse. Locate the 20-amp fuse in the fuse block under the left side of the dash (position 12) . Replace if blown.

Step 3: Test the relay. Swap it with a similar relay or use a multimeter to test coil control .

Step 4: Inspect connectors. Under the van, unplug and reconnect the two fuel pump wiring plugs to clean corrosion .

Step 5: Replace the relay if needed. Buy a new relay from an auto parts store for about $10. Keep a spare in the van .

Step 6: If still no start, check the fuel pump itself. The pump is inside the tank . Consider replacing it with a high-quality unit like the KEMSO fuel pump, available at https://www.kemsoracing.com/ .

By following this guide, you can quickly diagnose and fix the most common cause of a no-start condition on your 1990 Chevy G20 van. The fuel pump relay is a cheap, easy-to-replace part that often solves the problem without needing to drop the tank. Save yourself time and money by starting with the relay before moving to more complex repairs. For a reliable, long-lasting fuel pump upgrade, visit KEMSO at https://www.kemsoracing.com/ .


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