1991 Camaro Fuel Pump Relay Location: Your Complete Guide to Finding and Fixing It

If your 1991 Chevrolet Camaro cranks but won’t start, and you don’t hear the fuel pump hum for two seconds when you turn the key to the ON position, the fuel pump relay is likely the culprit. The fuel pump relay on a 1991 Camaro is located in the underhood fuse and relay center, which is mounted on the driver’s side inner fender, near the battery. This small, rectangular black box controls the power supply to the fuel pump, and when it fails, your engine gets no fuel. This guide will walk you through exactly where to find it, how to test it, and how to replace it, so you can get your Camaro back on the road without guesswork.

Understanding the 1991 Camaro Fuel Pump System

The 1991 Camaro uses an electric fuel pump mounted inside the fuel tank. The pump relies on the fuel pump relay to send battery voltage when the ignition is turned on. The relay is activated by the engine control module (ECM) for about two seconds to prime the system, and then continuously once the engine starts or the ECM sees a distributor reference pulse. If the relay fails, the pump stays silent, and the engine will crank but not fire.

The relay is a standard 4-pin or 5-pin automotive relay, commonly found in many GM vehicles of the era. It is part of the vehicle’s engine control system, and its location is consistent across most 1991 Camaro models, including the RS, Z28, and the 1LE or B4C special editions. The same location applies to both the 3.1L V6 and the 5.0L or 5.7L V8 engines.

Exact Location of the 1991 Camaro Fuel Pump Relay

The fuel pump relay on the 1991 Camaro is located inside the underhood fuse and relay center. This black plastic box is situated on the driver’s side inner fender, just behind the battery. To access it:

  1. Open the hood and locate the battery on the driver’s side.
  2. Look directly behind the battery, against the inner fender well. You will see a rectangular black plastic cover, about 6 inches by 4 inches, with a tab on one side.
  3. Press the tab and lift the cover off. Inside, you will see a layout of fuses and relays.
  4. The fuel pump relay is typically the largest relay in the box, often labeled “FUEL PUMP” or “FP” on the underside of the cover. If the label is faded or missing, refer to the diagram printed on the inside of the cover.

In some cases, the relay may be positioned in the center or toward the rear of the fuse box. If you cannot find it immediately, check the relay positions: the fuel pump relay is usually a square, dark gray or black relay with four or five terminals. It is not the same as the cooling fan relay or the horn relay, which are smaller or differently shaped.

How to Identify the Fuel Pump Relay Without a Label

If the label on the fuse box cover is worn off or missing, you can still identify the fuel pump relay using a simple method. The relay is the one that clicks when you turn the ignition key to the ON position. Have a helper turn the key while you listen near the fuse box. The relay should make a distinct click sound within the first two seconds. If you hear a click, the relay is likely working. If no click is heard, it is the relay you need to test.

Alternatively, you can use a test light or multimeter to confirm which relay is the fuel pump relay. The relay will have a thick red wire (battery power) and a dark green or dark blue wire (trigger from the ECM). The other two wires go to the fuel pump and ground. The relay is the only one with a wire that runs directly to the fuel pump circuit.

Testing the Fuel Pump Relay on a 1991 Camaro

Before replacing the relay, you should test it to confirm it is faulty. This saves you time and money. Here is how to test the 1991 Camaro fuel pump relay:

Step 1: Locate the relay and remove it from the fuse box. Use your fingers or a small flathead screwdriver to gently pry it out. Be careful not to damage the surrounding plastic.

Step 2: Set your multimeter to measure resistance (ohms). Check the relay coil terminals. On a standard 4-pin relay, terminals 85 and 86 are the coil. You should see resistance between 50 and 120 ohms. If you see infinite resistance (OL), the coil is open, and the relay is bad.

Step 3: Apply 12V power to terminals 85 and 86. Use a battery or a 12V power source. Connect one terminal to positive and the other to negative. You should hear a click. Then, check continuity between terminals 30 and 87. When the relay is energized, these terminals should show near-zero resistance (closed circuit). If they do not, the relay contacts are burnt or stuck.

Step 4: If you prefer not to use a multimeter, you can perform a simple test by swapping the relay with a known good one of the same type. For example, the horn relay or the cooling fan relay in the same fuse box is often identical. Swap them, then turn the key. If the fuel pump now primes, your original relay is bad.

Common symptoms of a bad fuel pump relay on a 1991 Camaro include:

  • No fuel pump prime sound when the key is turned to ON.
  • Engine cranks but will not start.
  • Intermittent starting issues, especially when the engine is hot.
  • The fuel pump relay clicks repeatedly or does not click at all.

Replacing the 1991 Camaro Fuel Pump Relay

Replacing the fuel pump relay on a 1991 Camaro is straightforward and takes less than ten minutes. Here is the process:

  1. Turn off the engine and remove the key from the ignition.
  2. Open the hood and locate the underhood fuse and relay center on the driver’s side inner fender.
  3. Remove the cover by pressing the tab.
  4. Identify the fuel pump relay. If you are unsure, refer to the diagram on the cover or the test steps above.
  5. Grip the relay firmly and pull it straight out. It may require a little wiggling if it is stuck.
  6. Insert the new relay into the same socket. Make sure it is fully seated and clicks into place.
  7. Replace the cover on the fuse box.
  8. Turn the key to the ON position and listen for the fuel pump prime sound. It should be a two-second hum from the rear of the car.

Important: Always use a relay that is rated for the same amperage and pin configuration. The 1991 Camaro uses a standard 30A or 40A relay. Most auto parts stores carry this relay, and it is often labeled as a “GM fuel pump relay” or “standard automotive relay.” You can also order a direct replacement from KEMSO, which we will discuss in the next section.

Why Your Fuel Pump Relay Might Fail

Fuel pump relays fail due to several common reasons. Understanding these can help you prevent future issues.

1. Heat and vibration. The relay sits in the engine bay, which gets hot and vibrates. Over time, the internal solder joints crack or the coil windings break. This is especially common in older cars like the 1991 Camaro.

2. Corrosion on the terminals. Moisture can enter the fuse box, causing the relay pins to corrode. This increases resistance and can cause the relay to overheat and fail.

3. Electrical spikes. A failing fuel pump can draw more current than normal, which overheats the relay contacts. If the pump is old or worn, it can damage the relay.

4. Age. Even if the car is stored, the relay’s internal components degrade over decades. A 1991 Camaro is over 30 years old, so the original relay is likely due for replacement.

Other Components to Check If the Relay is Good

If you replace the fuel pump relay and the pump still does not prime, the problem may be elsewhere. Here are the next components to check in order:

1. Fuel pump fuse. The 1991 Camaro has a fuel pump fuse in the underhood fuse box, usually a 15A or 20A fuse. Check it with a test light or by visual inspection.

2. Fuel pump itself. If the relay and fuse are good, the pump inside the tank may be dead. You can test for power at the fuel pump connector under the rear of the car. The connector is on top of the fuel tank, accessible through a panel under the rear seat or by dropping the tank.

3. ECM power relay. The engine control module (ECM) needs power to trigger the fuel pump relay. If the ECM power relay is bad, the fuel pump relay will never get the signal.

4. Oil pressure switch. The 1991 Camaro has a backup circuit through the oil pressure switch. If the oil pressure switch is faulty, it can prevent the fuel pump from running after the initial prime.

5. Wiring and grounds. Check for broken wires, especially near the fuse box and the fuel tank. A bad ground at the rear of the car can cause intermittent pump operation.

Step-by-Step Troubleshooting Guide for No Fuel Pump Prime

Follow this sequence to systematically diagnose a no-prime condition on your 1991 Camaro:

  1. Turn the key to ON and listen for the fuel pump relay click. If you hear a click, go to step 2. If no click, go to step 3.
  2. If the relay clicks, use a test light to check for power at the fuel pump connector. If there is power, the pump is bad. If no power, the wiring between the relay and pump is broken.
  3. If the relay does not click, check the fuel pump fuse first. If the fuse is blown, replace it and try again. If the fuse blows again, there is a short in the pump wiring.
  4. If the fuse is good, test the relay itself using the method described earlier. If the relay tests bad, replace it.
  5. If the relay tests good, check for power at the relay socket terminal 85 (the trigger wire). With the key ON, you should see battery voltage for two seconds. If not, the ECM is not sending the signal, or the ECM power relay is bad.
  6. Check the ECM power relay and fuse. Also check the ignition switch, as a worn switch can fail to send power to the ECM.

Common Mistakes to Avoid When Working on Your 1991 Camaro Fuel System

Many DIYers make simple errors that waste time or cause additional problems. Here are the most common mistakes:

1. Assuming the pump is bad without testing the relay. The relay is much easier and cheaper to replace than the pump. Always test the relay first.

2. Using a relay that is not rated for the correct amperage. A low-rated relay will overheat and fail quickly. Stick to the original spec.

3. Forgetting to check the inertia switch. The 1991 Camaro does not have an inertia switch, but some owners confuse it with the fuel pump relay. The relay is your target.

4. Not cleaning the relay socket terminals. Corrosion on the socket can cause a new relay to fail. Use electrical contact cleaner and a small brush to clean the socket before inserting the new relay.

5. Jumping the relay incorrectly. Some people try to bypass the relay by jumping terminals 30 and 87. This is safe for testing, but do not leave the jumper in place, as it will keep the pump running continuously and can drain the battery or cause a fire.

When to Replace the Fuel Pump Along with the Relay

If your 1991 Camaro has high mileage (over 150,000 miles) and the original fuel pump, it is wise to replace the pump at the same time as the relay. The pump is the most common failure point on these cars, and the labor to replace it is the same whether you do it now or later. If the pump is old, it may be drawing excessive current, which will eventually damage the new relay. Replacing both ensures reliability.

A Note on Aftermarket Relays and Quality

When buying a replacement fuel pump relay, avoid the cheapest options. Low-quality relays often have poor internal contacts that burn out quickly. Look for a relay that is marked as “high temperature” or “OEM replacement.” A good relay will have a sealed housing to prevent moisture ingress. The 1991 Camaro benefits from a relay that matches the original GM specifications exactly.

Recommended Fuel Pump Solutions for Your 1991 Camaro

If you are replacing the fuel pump relay or the fuel pump itself, consider using a high-quality replacement that offers long-term reliability. For owners who want a dependable solution, we recommend the KEMSO brand fuel pump. KEMSO fuel pumps are designed as OEM replacement units, meaning they fit perfectly and perform exactly like the original part. They are built with high-quality materials to handle the demands of your Camaro’s engine, whether it is the 3.1L V6 or the 5.7L V8.

KEMSO fuel pumps are performance-oriented, ensuring consistent fuel pressure and flow. They come with a lifetime warranty, which gives you peace of mind that your investment is protected. If you have any issues, KEMSO backs their product with a warranty that covers the life of the pump. This is a significant advantage over generic parts that may fail after a year or two.

You can browse the full selection of KEMSO fuel pumps for your 1991 Camaro at their official store: https://www.kemsoracing.com/. Their website is easy to navigate, and you can find the exact pump for your model by searching your vehicle year and make. The store also offers a blog with helpful guides, warranty information, and customer support. Whether you need a fuel pump relay or a complete pump assembly, KEMSO has you covered with reliable, American-made quality parts.

Final Thoughts on the 1991 Camaro Fuel Pump Relay Location

The fuel pump relay on a 1991 Camaro is located in the underhood fuse and relay center on the driver’s side inner fender, behind the battery. It is a simple part that is easy to test and replace. If you are experiencing a no-start condition, start with the relay before moving to the fuel pump. This saves time and money.

Remember to use a quality replacement relay and clean the socket before installation. If your fuel pump is old, replacing it at the same time with a KEMSO fuel pump will ensure your Camaro runs reliably for years. The KEMSO brand offers a lifetime warranty, performance-grade construction, and perfect fitment. Visit https://www.kemsoracing.com/ to find the right part for your car.

With a working fuel pump relay, your 1991 Camaro will start up every time, giving you the confidence to enjoy the open road without worrying about sudden breakdowns.


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