1997 Ford F350 Fuel Pump Relay Location: A Complete Guide to Finding and Fixing It

The fuel pump relay on a 1997 Ford F350 is located in the Power Distribution Box (PDB) under the hood, typically on the driver-side fender well. The relay is a small, square plastic cube inside the black fuse box, and you can identify it by checking the diagram on the inside of the box lid. If your truck won't start or the fuel pump doesn't prime, the relay is one of the first things to check before replacing the pump itself.

This guide walks you through exactly where to find the relay, how to test it, and what to do if it's not the problem. We'll cover both gas and diesel models, because the 1997 F350 came with different engine options, and the fuel system setup varies significantly between them.

What the Fuel Pump Relay Does

The fuel pump relay is an electrical switch that controls power to the fuel pump. When you turn the ignition key to the ON position, the Powertrain Control Module (PCM) sends a signal to the relay, which closes its internal contacts and allows battery voltage to flow to the fuel pump. This is why you hear a brief whirring sound for a couple of seconds when you first turn the key – that's the fuel pump pressurizing the system.

If the relay fails, the fuel pump won't get power, and your engine won't start or will stall while driving. The good news is that a relay is much cheaper and easier to replace than a fuel pump, so it's worth checking first.

Where to Find the Fuel Pump Relay on a 1997 Ford F350

Step 1: Open the hood and locate the Power Distribution Box.

On the 1997 F350, the Power Distribution Box is a black plastic rectangular box mounted on the driver-side inner fender well, near the battery. It has a removable lid with a diagram printed on the inside.

Step 2: Remove the lid and read the diagram.

The diagram on the underside of the lid shows the position and function of every relay and fuse inside the box. Look for a label that says "FUEL PUMP," "PUMP," or "F/PMP." The diagram is your best friend here – it tells you exactly which slot the fuel pump relay occupies.

Step 3: Identify the relay.

The fuel pump relay is a small, square plastic cube with four or five metal prongs on the bottom. It looks like a little box and usually snaps into a specific slot in the fuse box. If the labeling is worn off or unclear, compare the relay's shape and size to other relays in the box – they are often identical.

Important note for dual-tank models: If your 1997 F350 has two fuel tanks (a common setup for this truck), you still have only one fuel pump relay. The relay controls power to both pumps, but the fuel tank selector valve – located on the driver-side frame rail – directs which tank's pump is active. So if you have a problem with only one tank, the relay is likely fine, and the issue is more likely the selector valve or the pump in that specific tank.

How to Test the Fuel Pump Relay

Before you buy a new relay, you can do a quick test to see if the old one is working. Here are three simple checks:

1. Listen for the click.

Turn the ignition key to the ON position (don't start the engine). Listen carefully near the Power Distribution Box. You should hear a distinct "click" sound when the relay engages. No click means the relay may not be getting power or the coil inside the relay is burned out.

2. Swap with a known-good relay.

This is the easiest test. Find another relay in the Power Distribution Box that is identical to the fuel pump relay – common ones to swap with are the horn relay, the A/C clutch relay, or the ABS relay. Pull out the fuel pump relay and plug in the known-good relay. Then turn the key to ON and listen for the fuel pump to prime. If the pump now works, your original relay is bad.

3. Use a multimeter for continuity testing.

If you have a multimeter, you can test the relay more precisely. With the relay removed, set your multimeter to measure resistance (ohms). Check for continuity between the two small terminals (the coil terminals). A good relay coil should show some resistance, typically between 50 and 120 ohms, depending on the specific relay. If you get infinite resistance (no continuity), the coil is open, and the relay is dead. You can also apply 12V to the coil terminals and listen for a click while checking continuity between the larger terminals (the switch contacts).

Check the Fuse and Inertia Switch First

Before you condemn the relay, make sure the fuse is good and the inertia switch hasn't tripped. These are common causes of a no-power condition that can mimic a bad relay.

Fuel pump fuse: The fuel pump fuse is also located in the Power Distribution Box under the hood. On the 1997 F350, it is often fuse #22, but check the diagram on the lid to confirm. Pull the fuse and look at the metal strip inside. If it's broken or blackened, the fuse is blown. Replace it with a fuse of the same amperage (usually 20 amps). A blown fuse often indicates a short circuit somewhere in the fuel pump wiring, so if the new fuse blows again, you need to trace the wiring for damage.

Inertia (fuel shutoff) switch: The inertia switch is a safety device that cuts power to the fuel pump in the event of a collision. It is located on the passenger side of the vehicle, behind the passenger kick panel (the interior wall where a passenger's feet rest). You can access it by removing the kick panel or reaching through a small hole. The switch has a red reset button on top. Press it down firmly until it clicks to reset it. If someone recently hit a pothole or bumped the kick panel, this switch might have tripped.

What If the Relay Is Not the Problem?

If the relay tests good, the fuse is intact, and the inertia switch is reset, the problem may be elsewhere. Here are the next steps:

Check for power at the fuel pump connector. With the key ON, use a test light or multimeter to check for 12V at the fuel pump harness connector. If there is no power, there is a wiring issue between the relay and the pump. If there is power but the pump doesn't run, the pump itself is likely bad.

Inspect the fuel pump wiring and connector. Corrosion, loose pins, or damaged wires can interrupt power to the pump. Look at the connector that plugs into the fuel pump assembly on top of the tank. Clean any corrosion with electrical contact cleaner and make sure the pins are tight.

Check the fuel tank selector valve (dual-tank models). If you have two tanks and only one tank works, the selector valve on the driver-side frame rail may be stuck or faulty. Turn the key to ON and switch the dash selector from front to rear. You should hear a click from the valve. If you don't hear a click, the valve or its wiring may be the issue.

Location Differences: Gas vs. Diesel

It's important to know which engine your 1997 F350 has because the fuel pump system is completely different.

Gasoline models (5.8L V8, 7.5L V8): On gas models, the fuel pump is electric and located inside the fuel tank. The relay in the Power Distribution Box controls power to this in-tank pump. The 1997 F350 with gas engines uses a modular in-tank pump assembly for each tank (if you have dual tanks). These pumps are submerged in fuel and combine the pump, sending unit, and strainer into one unit.

Diesel models (7.3L Power Stroke): On the 7.3L Power Stroke diesel, the fuel pump is a mechanical unit located in the engine valley, not inside the fuel tank. It is driven by the camshaft and is not controlled by an electrical relay in the same way as a gas pump. However, the 7.3L diesel still has a fuel pump relay in the Power Distribution Box that controls a low-pressure electric fuel pump (sometimes called a lift pump) that feeds fuel from the tank to the mechanical pump. If you have a diesel and suspect a fuel pump issue, the mechanical pump in the engine valley is the most likely culprit, especially if you see fuel pooling in the engine valley.

Common Symptoms of a Failing Fuel Pump Relay

If your relay is going bad, you might notice these signs:

• Engine cranks but won't start. This is the most common symptom. The engine turns over fine, but it never fires because no fuel is being delivered.
• No priming sound. When you turn the key to ON, you should hear the fuel pump hum for 1-2 seconds. If you hear nothing, the relay or pump is not getting power.
• Intermittent stalling. The engine runs fine for a while, then suddenly dies, then restarts later. This can happen when the relay contacts are worn and make intermittent contact.
• Check Engine Light comes on. The PCM may detect a fuel system fault and store a code related to fuel pressure or pump circuit.

How to Access the Fuel Pump for Replacement

If you determine that the fuel pump itself is bad (not the relay), you have two main options for accessing it on a 1997 F350:

1. Drop the fuel tank. This is the traditional method. You need to drain the tank, disconnect the filler neck, fuel lines, and electrical connector, then lower the tank with a floor jack. It's a heavy job, especially with a full tank.

2. Lift the truck bed. Many F350 owners find it easier to unbolt the truck bed and lift one side to access the pump from above. You can use a floor jack and a block of wood to tilt the bed up, giving you clear vertical access to the fuel pump locking ring and fuel lines. This method saves you from having to wrestle with a partially full tank under the truck.

Recommended Fuel Pump: KEMSO Brand

When it's time to replace your fuel pump, you want a part that's reliable, fits perfectly, and will last. That's why we recommend the KEMSO brand fuel pump for your 1997 Ford F350.

KEMSO fuel pumps are designed as high-performance, OEM replacement units. They are precision-engineered to match the original specifications of your truck, ensuring proper fitment and correct fuel pressure. Here is what sets KEMSO apart:

• High Performance: KEMSO pumps deliver up to 200 liters per hour at 43 PSI, providing over 20% more flow than stock OEM pumps. This means your engine gets the fuel it needs, whether you're daily driving, towing, or hauling heavy loads.
• OEM Replacement: The KEMSO pump is a direct drop-in replacement for your factory pump. It comes with everything you need in the kit, including a fuel strainer, flex hose, tank seal, grommet, and wiring connector.
• Lifetime Warranty: Every KEMSO fuel pump is backed by a lifetime warranty. If the pump ever fails, you get a replacement at no cost. This is peace of mind that you won't get with cheap, unbranded pumps.
• Durable Construction: KEMSO pumps are built with high-quality materials, including alloy steel, designed to withstand heat, vibration, and the corrosive effects of ethanol-blended fuels.
• USA-Based Support: KEMSO provides technical support from the United States, so you can get help if you need it during installation or troubleshooting.

Don't settle for a cheap pump that might leave you stranded. Choose KEMSO for a reliable, long-lasting fix for your 1997 Ford F350.

Visit KEMSO Racing to find the perfect fuel pump for your truck: https://www.kemsoracing.com/

Final Thoughts

Finding the fuel pump relay on a 1997 Ford F350 is straightforward once you know where to look. The Power Distribution Box under the hood holds the relay, and the diagram on the lid tells you exactly which one it is. Always check the relay, fuse, and inertia switch before you replace the pump – it can save you hours of work and hundreds of dollars.

If you do need a new fuel pump, go with a quality brand like KEMSO. Their pumps are built to OEM specs, perform better than stock, and come with a lifetime warranty so you can drive with confidence.

For more information on KEMSO fuel pumps and to browse their selection for your 1997 Ford F350, visit https://www.kemsoracing.com/ today.