1993 Buick Century Fuel Pump Relay Location: A Complete Troubleshooting Guide

If your 1993 Buick Century cranks but won't start, the fuel pump relay is one of the first things you should check. The fuel pump relay on a 1993 Buick Century is located under the hood, on the passenger side, near the front of the engine compartment, mounted in the relay panel behind the passenger side headlight . More specifically, it sits in a bank of relays on the right front corner of the engine compartment, closest to the radiator . This small but critical component controls power delivery to the in-tank electric fuel pump. When it fails, your engine gets no fuel, and your car won't run.

The 1993 Buick Century came with either a 2.2L four-cylinder engine or a 3.3L V6 engine . Both engines use the same basic fuel pump circuit design, but the relay location and wiring colors remain consistent across both engine options. Knowing exactly where to find this relay and how to test it can save you hours of diagnostic time and hundreds of dollars in unnecessary repairs.

Understanding the Fuel Pump Relay's Role

The fuel pump relay acts as a switch that controls 12-volt power to the fuel pump. When you turn the key to the "ON" position, the engine computer (ECM) energizes the relay through a dark green wire with a white stripe . This allows power to flow from the battery through the relay and out to the fuel pump via a gray wire . The relay only stays closed (powered) during engine cranking and when the engine is running. If the engine stalls or the ignition is turned off, the relay opens and cuts power to the pump.

There is also a backup circuit through the oil pressure sender switch. Once the engine builds oil pressure, this switch provides a secondary power path to keep the fuel pump running even if the relay fails . This is why a car might start but then die shortly after—the oil pressure switch may not be working, or the oil pressure is too low .

Exact Location of the Fuel Pump Relay

Step 1: Open the hood and look at the passenger side. The relay panel is mounted on the inner fender, behind the passenger side headlight assembly . You will see a group of relays clustered together, usually on a bracket or in a plastic holder.

Step 2: Identify the relay that is closest to the radiator. According to multiple sources, the fuel pump relay is typically the relay nearest the radiator in this bank . On some models, the relay may be housed in a black plastic cylinder with a lid. Look carefully at the top of the lid—it should say something like "fuel pump relay" .

Step 3: Look for a loose red wire. There is a red wire with a female terminal that hangs near the left (driver side) strut tower. This wire connects to the fuel pump relay . If you find this wire, follow it to the relay.

Step 4: Confirm by wire colors. The fuel pump relay on a 1993 Buick Century has a specific set of wires in its connector: orange, red, dark green, gray, and black with white . If you pull the relay and see these five wire colors, you have found the correct relay. No other relay in the engine bay uses this exact color combination .

How to Test the Fuel Pump Relay

Before you buy a new relay, you should test the existing one. This is a simple process that anyone can do with a few basic tools.

What you need: A 12-volt test light or a digital multimeter, a short piece of wire with alligator clips, and a fuse (10-amp) for safety.

Test 1: Check for power at the relay socket. Remove the relay and turn the key to the "ON" position. Use your test light or multimeter to check for 12 volts on the orange wire terminal in the relay socket. If there is no power, check the fuel pump fuse first. The fuel pump fuse is also located under the hood, on the passenger side, in the front engine area under the passenger side of the radiator . It is mounted in the same relay panel.

Test 2: Use a jumper wire to bypass the relay. This is the most definitive test. Take a short piece of wire with a 10-amp inline fuse and connect battery positive (+) to the gray wire terminal in the relay socket . If the fuel pump runs, the relay is bad. If the pump does not run, the problem is elsewhere—either the pump itself, the wiring, or a bad ground.

Test 3: Check the control circuit. With the relay removed, turn the key to the "START" position. Check for 12 volts on the dark green wire terminal. This wire comes from the ECM and should only have power during cranking . If you do not see power here, the ECM may not be triggering the relay, or there is a problem with the crank sensor or ignition switch.

Common Problems and Solutions

Problem 1: No power to the fuel pump at all. This is usually caused by a bad relay, a blown fuse, or a broken wire. Start by checking the fuse. If the fuse is good, test the relay using the jumper wire method described above. If the pump runs with the jumper, replace the relay. If the pump still does not run, the pump itself may be bad, or there is a wiring issue between the relay and the pump.

Problem 2: The car starts but then dies after a few seconds. This is a classic symptom of a bad oil pressure sender switch. The relay provides power during cranking, but once the key is released, the oil pressure switch is supposed to take over . If the switch is faulty or oil pressure is too low, the pump loses power and the engine dies. Check the oil pressure first, then test the oil pressure switch.

Problem 3: Intermittent stalling, then restarts after sitting. This can be caused by a failing relay that works when cold but fails when hot. It can also be caused by a clogged fuel filter or a failing fuel pump. One owner reported that after cleaning a clogged fuel filter, the pump still had no power, and the problem turned out to be a simple oversight—the pump connector was not plugged back in . Always double-check your connections.

Problem 4: The pump runs constantly, even with the key off. This indicates a shorted relay or a stuck relay. The orange wire supplies constant battery power to the relay . If the relay is stuck closed, the pump will run continuously. Replace the relay immediately to avoid draining the battery and potentially damaging the fuel pump.

Fuel Pump Relay Wire Color Guide

Here is a quick reference for the wire colors at the fuel pump relay connector on a 1993 Buick Century :

• Orange: Constant 12-volt power from the battery (always hot)
• Red: 12-volt power when the ignition is in the "ON" position
• Dark Green with White Stripe: 12-volt power from the ECM only during cranking ("START" position)
• Gray: 12-volt power output to the fuel pump
• Black with White: Ground

If you need to test the system manually, you can jump the correct terminals. Orange to gray makes the pump run constantly (key on or off). Red to gray makes the pump run only when the key is on. Dark green to gray makes the pump run only during cranking .

Where to Find the Fuel Pump Fuse

The fuel pump fuse on a 1993 Buick Century is located in the same general area as the relay. It is under the hood, on the passenger side, mounted in the front engine area near the passenger side of the radiator . The fuse is typically in a plastic carrier and may be part of the relay panel itself. Check all fuses in this panel with a test light, even if they look good visually. Some fuses are not clearly marked, so testing each one is the only way to be sure .

Replacement Parts for the 1993 Buick Century Fuel Pump Relay

If you determine that the relay is faulty, the genuine OEM part number for the 1993 Buick Century fuel pump relay is 19118886 . This part also replaces the following numbers: 12177235, 12135086, 12135005, 12193613, 12177233, 84095360, 12193601, 12193603, 12193611, 12135085, 12077867, 12077864, 12088577, and 19131161 . The relay fits all 1993 Buick Century submodels, including Custom, Limited, Special, and station wagon variants, with both 2.2L and 3.3L engines .

The relay weighs about 0.40 pounds and measures approximately 3.2 x 2.2 x 2.2 inches . It is a direct replacement part, meaning no modification or special tools are needed for installation.

Step-by-Step Relay Replacement Procedure

Replacing the fuel pump relay is one of the easiest repairs you can do on a 1993 Buick Century. No special tools are required, and the whole job takes less than 10 minutes.

Step 1: Locate the relay. Find the relay panel on the passenger side, behind the headlight, as described above.

Step 2: Identify the correct relay. Look for the relay with the orange, red, dark green, gray, and black/white wires . If you are unsure, look for the black plastic cylinder with a lid that says "fuel pump relay" .

Step 3: Remove the old relay. Simply pull the relay straight out of its socket. It is held in by friction, so no tools are needed. If it is stuck, gently rock it back and forth while pulling.

Step 4: Install the new relay. Push the new relay firmly into the socket until it is fully seated. Make sure it clicks into place.

Step 5: Test the system. Turn the key to the "ON" position. You should hear the fuel pump prime for about 2 seconds. If you do not hear it, turn the key to "START" and try to start the engine. If the engine starts and runs, the repair is complete.

Why Your Fuel Pump May Still Not Work After Replacing the Relay

If you replace the relay and the fuel pump still does not work, you need to dig deeper. Here are the most common reasons for a no-power condition after relay replacement:

Bad fuel pump. The pump itself may be dead. You can test this by running a jumper wire from the battery positive terminal directly to the gray wire at the relay socket . If the pump runs, the pump is fine. If not, the pump needs to be replaced.

Blown fuse. Even if the relay is good, a blown fuse will prevent power from reaching the relay. Check the fuel pump fuse in the underhood fuse panel .

Bad ground. The fuel pump relies on a good ground connection. Check the black/white wire at the relay for continuity to ground. Also check the ground wire near the fuel tank.

Corroded or damaged wiring. Over time, the wiring harness can become corroded, especially in areas exposed to road salt and moisture. Inspect the wires from the relay to the fuel pump for any signs of damage, melting, or corrosion.

Faulty ECM. In rare cases, the engine computer may not be sending the signal to energize the relay. This is less common but can happen if the ECM has failed or if there is a problem with the crank sensor.

When to Replace the Fuel Pump Instead of Just the Relay

If your 1993 Buick Century has high mileage (over 100,000 miles) and you are experiencing fuel delivery problems, it may be time to replace the entire fuel pump. The fuel pump is located inside the fuel tank, which means you will need to drop the tank to access it . This is a more involved repair, but it is necessary if the pump itself has failed.

Symptoms of a bad fuel pump include: the engine cranks but will not start, you cannot hear the pump priming when you turn the key, the car stalls under load or at high speeds, and the engine sputters or hesitates during acceleration. If you have already replaced the relay and filter and the problem persists, the pump is likely the culprit.

KEMSO Fuel Pump Recommendation

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Additional Tips for 1993 Buick Century Owners

Always replace the fuel filter when you replace the fuel pump. A clogged fuel filter can cause the new pump to fail prematurely . The fuel filter on a 1993 Buick Century is located along the frame rail under the driver side of the car, near the rear wheel. You will see two black fuel lines, and one will be connected to a canister-shaped filter .

Use a fuel pressure gauge to confirm the system is working correctly. The fuel pressure should be within specifications for your engine. Testing the pressure takes the guesswork out of diagnosis and ensures you are not chasing a phantom problem.

Keep a spare relay in your glove box. The fuel pump relay is a common failure point, and having a spare on hand can save you from being stranded. The relay is inexpensive and easy to replace on the side of the road.

Understand the oil pressure switch backup circuit. If your car starts but dies after a few seconds, suspect the oil pressure switch before the relay. The switch is located near the oil filter and is relatively inexpensive to replace. If the switch is bad, the pump will stop receiving power once the key is released from the start position .

Check for a poor ground connection. One owner of a similar Buick model found that a poor ground was the cause of their fuel pump problem . Ground connections can corrode over time, especially in areas exposed to moisture and road salt. Clean and tighten all ground connections in the engine bay.

Final Thoughts

The 1993 Buick Century fuel pump relay is located under the hood on the passenger side, behind the headlight, in the relay panel closest to the radiator . It is identified by its wire colors: orange, red, dark green, gray, and black with white . Testing the relay is simple and can save you from replacing parts unnecessarily. If the relay is bad, replace it with a genuine OEM part or a high-quality aftermarket equivalent. If the pump itself needs replacement, consider a KEMSO fuel pump for reliable performance backed by a lifetime warranty.

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