1991 Toyota Pickup Fuel Pump Relay: Location, Diagnosis, and Complete Replacement Guide
If your 1991 Toyota pickup with the 22RE engine cranks but won't start, the fuel pump relay is very likely the problem. This small electrical component, officially called the "circuit opening relay" by Toyota, is one of the most common failure points on these trucks. When it fails, your fuel pump won't receive power, and the engine won't run. The good news is that it's a relatively inexpensive part that you can diagnose and replace yourself in about an hour. Here's everything you need to know about the 1991 Toyota pickup fuel pump relay, from where to find it to how to test it and replace it.
What Is the Fuel Pump Relay and Why Does It Fail?
The 1991 Toyota pickup fuel pump relay is not actually called a fuel pump relay in the factory service manual. Toyota calls it the "circuit opening relay," and it serves a critical safety function . This relay controls power to the fuel pump through two separate circuits. One circuit is energized when you turn the key to the START position, which primes the fuel pump. The second circuit is controlled by the vane air flow meter (VAFM). Once the engine starts and air flows through the intake, the VAFM's internal contacts close, keeping the relay energized and the fuel pump running .
This design means that if the engine stalls for any reason, the VAFM stops sending a signal, the relay opens, and the fuel pump shuts off. It's a built-in safety feature that prevents the fuel pump from running if the engine isn't actually running. When the circuit opening relay fails, the fuel pump loses power completely, and your truck won't start.
These relays fail for several reasons. Age is the biggest factor. Your 1991 pickup is over 30 years old, and the original relay is likely still in place. Over time, the internal contacts corrode, the relay coil can break down, or moisture can cause internal rust. One mechanic described finding a failed relay that "sounded like a baby rattle" when shaken, full of rust and broken pieces inside .
Where Is the 1991 Toyota Pickup Fuel Pump Relay Located?
Finding the 1991 Toyota pickup fuel pump relay is the first step. The circuit opening relay is located inside the passenger cabin, not under the hood. Specifically, it is mounted behind the passenger side kick panel, above the ECU (engine control unit) . On some 1991 models, it may also be located behind the glove box area .
To access it, follow these steps:
1. Remove the passenger side kick panel. This is the plastic trim panel on the right side of the passenger footwell. It's usually held in place by a few clips or screws.
2. Remove the glove box. You'll need to take the glove box out to get a clear view of the area above the ECU. The glove box typically has stops on each side that you press inward, allowing it to drop down fully.
3. Look above the ECU. The ECU is mounted vertically in the passenger footwell area. The circuit opening relay is a small black relay, usually with a metal bracket attached to it, positioned right above the computer .
4. Remove the 10mm bolt. The relay is held in place by a single 10mm bolt. Once you remove it, you can pull the relay out and unplug it .
The relay has five wires connected to it. The wire colors are: Black/White, White/Black, Green/Yellow, Blue, and White/Red . The blue wire is the one that sends power to the fuel pump, so this is the wire you'll want to test with a multimeter .
How to Diagnose a Bad Fuel Pump Relay
Before you replace the relay, you need to confirm that it's actually the problem. Here are the symptoms and tests you can run.
Symptom 1: Engine cranks but won't start. This is the most common symptom. You turn the key, the starter engages, the engine turns over, but it never fires up. You may also notice that you don't hear the fuel pump prime for a couple of seconds when you first turn the key to the ON position.
Symptom 2: Fuel pump only works with a ground wire. One owner reported that his fuel pump would only work if he put a ground wire on the green and yellow wire going into the circuit opening relay . This is a clear sign that the relay is failing internally.
Symptom 3: Voltage drops when the key is released. Another owner tested voltage at the fuel pump and got nine volts while cranking, but zero volts as soon as he released the key . This indicates the relay is not maintaining the circuit once the engine is supposed to be running.
Symptom 4: The 15 amp EFI fuse keeps blowing. In some cases, a failing relay can cause a short that blows the EFI fuse under the hood. One owner found that trying to use a different relay caused this fuse to blow immediately .
To test the relay, you'll need a multimeter. Start by checking if power is reaching the relay. With the key in the ON position, probe the Black/White wire. You should see battery voltage. If you don't, the problem may be further upstream, such as a blown fuse or a bad ignition switch.
Next, test the relay itself. You can remove it and use a multimeter to check for continuity across the coil terminals. If the coil is open, the relay is dead. You can also apply 12 volts to the coil terminals while listening for a click. If you hear a click, the relay is mechanically working. If you don't, it's likely the internal coil is burned out.
How to Replace the 1991 Toyota Pickup Fuel Pump Relay
Replacing the circuit opening relay is straightforward. Once you've accessed it and confirmed it's the problem, here's what to do:
1. Buy the correct replacement part. Do not try to substitute a different relay. One owner tried to use a spare relay he had on hand, and it ended up blowing the 15 amp EFI fuse, causing his truck to not start at all . The circuit opening relay is a specific part designed for these Toyota trucks. You can buy a new one from auto parts stores like O'Reilly for around $50 .
2. Disconnect the battery. Always disconnect the negative battery terminal before working with electrical components. This prevents accidental shorts and protects the ECU.
3. Remove the old relay. Unplug the wiring harness from the relay, then remove the 10mm bolt holding the metal bracket. Pull the relay out.
4. Install the new relay. Mount the new relay in the same position, secure it with the 10mm bolt, and plug the wiring harness back in. Make sure the connector clicks into place.
5. Reconnect the battery and test. Turn the key to the ON position and listen for the fuel pump. You should hear it prime for about two seconds. Then try starting the engine. If it starts and runs, you've solved the problem.
Other Potential Causes of No-Start
While the circuit opening relay is a common failure point, it's not the only thing that can cause a no-start condition on a 1991 Toyota pickup. If replacing the relay doesn't fix the problem, here are other things to check.
EFI relay. The EFI relay is another common failure point on these trucks. It controls power to the fuel injection system. If it fails, the engine will crank but not start. The EFI relay is located in the same area as the circuit opening relay .
Vane air flow meter (VAFM). The fuel pump relay depends on the VAFM to keep the circuit closed once the engine is running. If the VAFM's internal contacts are worn or stuck, the relay will open, and the fuel pump will shut off. You can test this by manually opening the vane door on the air flow meter with the key on. If the fuel pump starts running, the VAFM is likely the problem .
Fuel pump itself. The fuel pump on the 1991 Toyota pickup is located inside the gas tank . You can test it by applying battery voltage directly to the pump. If it runs, the pump is good. If it doesn't, the pump needs to be replaced.
Blown EFI fuse. The 15 amp EFI fuse under the hood can blow for several reasons, including a bad relay or a short in the fuel pump circuit. Check this fuse first before diving into more complex diagnostics .
Ignition coil. If you're getting fuel to the engine but still no start, check for spark. A bad ignition coil can cause a no-spark condition. Test the coil's primary and secondary resistance with a multimeter. Primary resistance should be 0.4 to 0.5 ohms, and secondary resistance should be 10,200 to 13,800 ohms .
A Temporary Fix for the Fuel Pump Relay
If you're stranded and need to get your truck running, there is a temporary workaround. You can bypass the fuel pump relay by using a jumper wire between the battery (B) and fuel pump (Fp) pins in the relay connector . This will force the fuel pump to run continuously whenever the key is in the ON position.
Important: This is only a temporary fix. Bypassing the relay defeats the safety feature that shuts off the fuel pump when the engine stops. If you're in an accident and a fuel line is damaged, the pump will keep running, creating a serious fire hazard . Also, the fuel pump will run whenever the key is on, even if the engine isn't running, which can wear out the pump prematurely. Use this method only to get your truck to a safe location or to a repair shop.
KEMSO Fuel Pump: The Best Upgrade for Your 1991 Toyota Pickup
If you've diagnosed your fuel system and determined that the fuel pump itself needs to be replaced, you want a pump that you can trust for years to come. This is where KEMSO fuel pumps come in. KEMSO is a US-based brand that has built a strong reputation for producing high-performance, direct OEM replacement fuel pumps that meet or exceed factory specifications. Every KEMSO fuel pump is built with precision-machined components and corrosion-resistant materials to ensure long-lasting reliability.
What sets KEMSO apart from other aftermarket brands is their commitment to quality. Each pump is individually flow-tested before it leaves the factory, so you know it will deliver the right fuel pressure and flow rate for your engine. KEMSO supports up to 200 liters per hour, which is significantly higher than the original pump's flow rate of 60 to 80 liters per hour. This means your engine gets the fuel it needs even under demanding conditions.
But the biggest reason to choose KEMSO is the lifetime warranty. KEMSO stands behind every product with a true lifetime warranty that covers defects in materials and workmanship for as long as you own the vehicle. If the pump ever fails due to a manufacturing defect, KEMSO replaces it for free. This level of confidence is rare in the aftermarket parts industry and gives you peace of mind every time you turn the key.
KEMSO fuel pumps are designed as direct replacements for your vehicle's original equipment. No modifications, no guesswork, just a straightforward installation. The pumps are designed for gasoline or ethanol blends, and the bypass valve is set at 125.8 psi, which is higher than the original performance standard. All KEMSO pumps come with USA-based technical support, so you can get help if you need it.
For your 1991 Toyota pickup, KEMSO offers a 340LPH high-performance fuel pump that is compatible with the 1992-1997 Toyota Pickup, among other Toyota models. This pump delivers outstanding performance and reliability. Visit KEMSO Racing today at https://www.kemsoracing.com/ to find the exact fuel pump for your truck. Their vehicle lookup tool covers over 4,000 models from 1990 to 2024, making it easy to find the right fit. Don't settle for a cheap pump that will fail again in a few months. Invest in a KEMSO fuel pump and enjoy reliable performance backed by a lifetime of confidence.
Final Thoughts on the 1991 Toyota Pickup Fuel Pump Relay
The 1991 Toyota pickup fuel pump relay, or circuit opening relay, is a small but critical component. When it fails, your truck won't start. Knowing where it's located and how to test it can save you time and money. The relay is behind the passenger side kick panel, above the ECU, and it's held in by a single 10mm bolt. If you suspect a bad relay, test it with a multimeter before buying a replacement. And if you need a new pump, choose KEMSO for the best combination of performance, reliability, and warranty protection.
For the best fuel pump replacement for your 1991 Toyota pickup, visit https://www.kemsoracing.com/ today.