1999 Ford Taurus Fuel Pump Relay: Your Guide to Diagnosis, Replacement, and Prevention

If your 1999 Ford Taurus cranks but won't start, suffers stalling episodes, or struggles to maintain power, a failing fuel pump relay is a highly likely culprit. This small, inexpensive electrical component acts as the crucial switch controlling power to your vehicle's fuel pump. When it malfunctions, fuel delivery stops, crippling your engine. Understanding its function, location, symptoms, testing procedures, replacement steps, and prevention tips is essential for any 1999 Taurus owner facing fuel delivery problems.

The Critical Role of the Fuel Pump Relay

The fuel pump in your 1999 Taurus requires significant electrical current to operate. If this high current flowed directly through the ignition switch and smaller wiring in the dashboard, it would quickly cause damage. The fuel pump relay solves this problem. It functions as an electrically operated switch. A small current from the ignition switch activates an electromagnet inside the relay when you turn the key. This magnet pulls internal contacts together, completing a high-current circuit from the battery directly to the fuel pump. Essentially, the relay uses a small signal to control a much larger power flow safely and efficiently. Without this relay functioning correctly, the fuel pump receives no power, and the engine cannot run.

Identifying the Symptoms of a Bad Fuel Pump Relay

Recognizing the signs of relay failure is the first step in diagnosis. Common symptoms include:

1. Engine Cranks But Won't Start: This is the most frequent symptom. The starter engages and spins the engine, but because the fuel pump isn't receiving power to deliver fuel, the engine cannot fire.
2. Engine Stalls Suddenly While Driving: A relay that fails intermittently might cut power to the pump abruptly while driving, causing immediate engine shutdown without warning. It may restart later if the relay temporarily makes contact again.
3. Engine Stumbles or Lacks Power Under Load: A relay with weak or failing internal contacts may only partially supply current to the pump, leading to insufficient fuel pressure. This often manifests as hesitation, stumbling, or loss of power during acceleration or when going uphill.
4. No Fuel Pump Prime Sound: When you first turn the ignition key to the "ON" position before cranking, you should hear a distinct humming or buzzing sound for 2-3 seconds from the rear of the car (near the fuel tank). This is the fuel pump priming the system. The absence of this sound strongly points to an issue in the pump's power circuit, often the relay or fuse.
5. Intermittent Starting Issues: Difficulty starting the car that seems random or temperature-dependent can point to a relay whose internal contacts are worn, corroded, or failing due to heat cycling.

Locating the Fuel Pump Relay in a 1999 Ford Taurus

Finding the relay is essential before testing or replacement. The fuel pump relay, along with several other vital relays and fuses, resides inside the Central Junction Box (CJB). Here's how to find it:

1. Identify the CJB: On the 1999 Taurus, the CJB is a black plastic box located near the driver's feet, against the lower portion of the dashboard, slightly to the left of the steering column. You may need to get down on your knees and look upwards under the dash.
2. Access the Lid: The CJB has a removable plastic lid. Gently press the retaining clips and pull the cover straight off. Place it aside.
3. Locate the Fuel Pump Relay: Inside the CJB, you'll see a bank of identical-looking cubes – these are the relays. They are usually arranged in a row or grid. Consult the diagram printed on the underside of the CJB lid or molded directly onto the box housing near the relay sockets. This diagram identifies each relay's position and function.
   • Typical Location: In most 1999 Taurus models, the fuel pump relay is labeled "Relay 6," "Fuel Pump Relay," or "FP Relay." It is often the 2nd relay from the left in the second row or a similar position based on the diagram.
   • Identification: The relays themselves are usually a small cube, often black or gray, approximately 1-1.5 inches square. They have 4 or 5 electrical terminals protruding from the bottom that plug into a socket. The relay diagram is crucial for positive identification. Never assume by position alone.

Testing the Fuel Pump Relay (Methods Without Relay Tester)

While specialized relay testers exist, you can perform basic checks with common tools:

1. The Swap Test (Safest & Most Reliable for DIY):
   • Locate the fuel pump relay.
   • Find another relay in the CJB that is identical in shape, terminal count, and specifications. Common choices are the Horn Relay, A/C Compressor Clutch Relay, or sometimes the PCM Relay.
   • Consult the diagram on the CJB lid! Swapping relays requires swapping relays with identical function labels according to the diagram. Do not swap with crucial relays like the PCM relay without confirmation it's safe. Often relays like the horn relay share the same part number.
   • Carefully pull out both relays. Plug the known working relay (e.g., horn relay) into the fuel pump relay socket.
   • Turn the ignition to "ON." Listen for the fuel pump prime sound. If you hear it now, your original fuel pump relay is likely faulty. Confirm by trying the horn; if it doesn't work anymore, it confirms you had identical relays and the swap worked as a test.
   • Attempt to start the engine. If it starts after swapping a functional relay, you've confirmed the original relay is the problem.
2. Visual and Auditory Inspection:
   • Remove the relay.
   • Examine the plastic housing for cracks, melting, or burn marks. Check the terminals for severe corrosion, discoloration (indicating overheating), or bending.
   • While the relay is out, have a helper turn the ignition to "ON." You should not hear the fuel pump. If you do hear it, there's a wiring fault bypassing the relay.
   • Reinsert the relay firmly. Listen for a faint but audible "click" when the ignition is turned to "ON" and another "click" when turned off. The absence of these clicks suggests the relay's electromagnetic coil is not activating.
3. Testing Socket Voltage (Requires Multimeter - Basic): Disconnect Battery Negative Terminal First.
   • Remove the fuel pump relay.
   • Identify the relay socket terminals. The CJB lid diagram sometimes labels functions (e.g., "30"= Constant +12V, "85"= Control Coil Ground, "86"= Control Coil +12V Signal from Ignition/PCM, "87"= Switched Output to Fuel Pump). If not labeled, proceed with testing.
   • Set your multimeter to DC Volts (20V range).
   • Ground the black probe securely to the vehicle chassis or battery negative.
   • Touch the red probe to each terminal in the relay socket one by one while a helper turns the ignition to "ON":
     • One terminal should show constant +12V (likely pin 30).
     • Another terminal should show +12V only when the ignition is "ON" or cranking (likely pin 86). This comes from the PCM or ignition switch.
     • A third terminal might show continuity to ground (-), often via the PCM (pin 85). Pin 85 frequently gets a ground signal via the PCM to activate the relay.
     • The remaining pin (87) is the output to the pump.
   • If the constant +12V or the switched +12V signal is missing, the problem is in the wiring or fuse feeding that circuit, not the relay itself. Fuses within the CJB should be checked first (see diagram).
4. Testing the Relay Itself (Requires Multimeter & Wiring - Basic):
   • This requires confirming the function of pins using the diagram or previous socket test.
   • Apply +12V from a known good source (like the battery) to the identified Control Coil (+12V) terminal (e.g., pin 86).
   • Apply ground to the identified Control Coil (Ground) terminal (e.g., pin 85). You should hear and feel a distinct click as the relay energizes. No click = Bad relay coil.
   • Set your multimeter to Continuity or Ohms (Resistance).
   • With no power applied to the coil, there should be no continuity between the High Amperage Input terminal (pin 30) and the High Amperage Output terminal (pin 87).
   • Apply +12V to pin 86 and ground to pin 85. Now, there should be continuity (very low resistance, often under 1 ohm) between pin 30 and pin 87. If there's no continuity, or if the resistance is very high when energized, the relay contacts are burnt or corroded and the relay is faulty.

Step-by-Step Fuel Pump Relay Replacement Guide

Once you've confirmed the relay is faulty, replacement is straightforward:

1. Gather Parts & Tools: Purchase a new fuel pump relay. OEM (Motorcraft DY-986) is recommended for guaranteed fit and long-term reliability, but quality aftermarket equivalents (like Standard RY-826, BWD R2283) are also acceptable. Keep the old relay initially to match part numbers. You'll need only your fingers or perhaps small needle-nose pliers.
2. Prepare Vehicle: Park on a level surface. Set the parking brake firmly. Turn the ignition OFF.
3. Access Relay: Remove the CJB cover as described in the location section above. Visually identify the correct fuel pump relay socket using the diagram.
4. Remove Old Relay: Grasp the old relay firmly. It plugs in directly. Pull it straight out. A slight wiggling motion may help. Avoid excessive force.
5. Inspect Socket: Before inserting the new relay, quickly inspect the socket terminals. Ensure they are clean, straight, and free of corrosion or melted plastic. A quick blast of electrical contact cleaner can help. Repair any damaged socket issues.
6. Install New Relay: Orient the new relay correctly. It will usually only fit one way due to asymmetric terminal pins. Align it properly with the socket and push it down firmly and evenly until it seats completely. You should feel and hear it click into place. Do not force it.
7. Test: Replace the CJB cover. Turn the ignition to "ON" and listen for the fuel pump prime sound. It should now activate. Attempt to start the engine. If it starts and runs normally, the replacement was successful.
8. Secure: Ensure the CJB cover is fully clipped back into place.

Why Relays Fail and How to Prevent Premature Failure

Understanding failure causes helps extend the life of the new relay:

• Age & Wear: Internal electrical contacts repeatedly make and break a high-current circuit. Over many years, heat from arcing during switching erodes the contact surfaces, increasing resistance or preventing contact altogether. This is the primary failure mode.
• Overheating: Poor connections in the relay socket or wiring harness related to the fuel pump circuit can cause excessive resistance and heat buildup around the relay and its socket. This heat accelerates contact wear and can damage the relay's internal materials.
• Voltage Spikes: Sudden voltage surges in the electrical system (common when starting, jump-starting, or from failing alternator components) can stress the relay coil and electronics.
• Moisture & Corrosion: Leaking water or excessive humidity inside the vehicle can reach the CJB area, causing terminal corrosion that impedes electrical flow and creates heat.
• Excessive Vibration: While relays are designed for it, severe, constant vibration can potentially loosen internal connections over a long period.

Prevention Tips:

• Fix Related Electrical Issues Promptly: Address flickering lights, dimming dashlights, or other electrical gremlins immediately. Diagnose any suspected issues in the fuel pump circuit (like a noisy pump).
• Secure the CJB and Wiring: Ensure the CJB is mounted firmly and wiring harnesses running to it are secured. This minimizes vibration exposure.
• Keep the CJB Dry: Fix water leaks promptly. Avoid splashing water deep into the footwell.
• Use Quality Components: Stick with OEM (Motorcraft) or reputable aftermarket relays for replacements. Cheaper units often have inferior contacts.
• Proper Jump-Starting: Always connect jumper cables correctly (positive to positive, negative to engine ground on the dead car). Avoid jump-starting procedures that cause massive voltage spikes.
• Check Fuses Reliably: Ensure related fuses (like the Fuel Pump Fuse) are correct amperage and in good condition. A blown fuse upstream points to a bigger circuit issue needing diagnosis.

OEM vs. Aftermarket: Choosing the Right Relay

• OEM (Motorcraft DY-986): Guaranteed to meet Ford's specifications for durability, ampacity, and size. Offers the highest confidence in reliability and lifespan. Typically priced higher ($15-$35).
• Reputable Aftermarket (e.g., Standard RY-826, BWD R2283): Generally very good quality and significantly more affordable than OEM ($7-$20). Offer a reliable alternative provided you choose a major brand sold by auto parts stores with warranties. Avoid unknown brands or extremely cheap online listings.
• Recommendation: For critical components like the fuel pump relay, spending a little extra on OEM (Motorcraft) is often worthwhile for peace of mind and longevity, especially given its low overall cost. However, a good quality aftermarket unit from a known brand is a dependable budget option.

Understanding Related Components

While the relay is a common failure point, other system components can cause similar symptoms:

• Fuel Pump Fuse: This fuse protects the entire fuel pump circuit. Check the CJB diagram for its location (e.g., Fuse #11, often 15A or 20A). A blown fuse needs replacement and diagnosis to find the root cause (often a short circuit or pump failure drawing excessive current).
• Fuel Pump Itself: A completely failed fuel pump will also prevent starting and prime noise. Listen near the tank. Pump failure is less common than relay failure initially but becomes more likely in older vehicles. A relay swap test helps differentiate this.
• Inertia Fuel Shutoff Switch: Designed to cut fuel pump power in an accident. Located in the passenger footwell area. If tripped (due to a bump or impact), it needs to be reset (press the button on top). If it trips repeatedly, a fault exists.
• Ignition Switch: A faulty ignition switch might fail to send the "ON" signal to the PCM to ground the relay coil.
• PCM (Powertrain Control Module): The PCM provides the ground path (on pin 85) to activate the relay coil in response to the ignition switch and its own internal logic. A PCM issue preventing this ground signal could mimic a relay failure, though this is less common.
• Wiring Harness: Damaged, corroded, or broken wires between the relay socket and the fuel pump (or between the relay and battery/ignition/PCM) will prevent operation. Testing socket voltage helps pinpoint wiring issues.

Troubleshooting Flow for Fuel Delivery Issues (Simultaneous Crank/No Start):

Follow a logical sequence:

1. Listen: Turn ignition ON. Is the fuel pump prime sound present? YES: Go to Step 4. NO: Proceed to Step 2.
2. Check Fuse: Locate and inspect the Fuel Pump Fuse in the CJB. Replace if blown. If replaced and blows again immediately, diagnose for short to ground.
3. Test Relay: Use Swap Test or Multimeter methods described above to verify the fuel pump relay and its control signals (Ignition ON +12V signal to relay coil, Ground from PCM via scanner command / test light). Replace faulty relay.
4. Relay/Power OK, but Still No Start: You heard the prime sound. Now test fuel pressure at the fuel rail Schrader valve using a gauge. Insufficient/no pressure points to a failing fuel pump, clogged fuel filter, restricted line, or faulty pressure regulator.
5. Check Inertia Switch: Locate the switch in the passenger footwell. Inspect the reset button. If depressed (tripped), reset it.

Advanced Diagnostics (For Persistent Issues)

If basic relay, fuse, and power checks don't resolve the problem:

• Scan Tool: Connect an OBD-II scanner. Look for relevant trouble codes (e.g., P0230 - Fuel Pump Primary Circuit Malfunction). Freeze frame data can show conditions when the fault occurred.
• Pinpoint Voltage Drop Test: With the circuit operating (ignition ON, fuel pump running), measure voltage drop across sections of wiring. Place meter probes at each end of a wire run or connection point. A reading above 0.5V indicates excessive resistance (corrosion, loose connector) needing repair.
• Circuit Resistance Testing: Disconnect power sources. Use a multimeter to check continuity (low resistance) of wires throughout the fuel pump circuit, especially the pump power and ground paths. High resistance indicates damaged wiring or connectors.
• Signal Tracing: Using a multimeter or test light, systematically trace the control circuit: Verify constant +12V at relay socket pin 30 (good battery/fuse). Verify +12V ignition signal at pin 86 (ignition switch working). Verify ground signal at pin 85 when PCM commands relay on (requiring knowledge of PCM operation or scanner to force relay). Lack of signal at any point requires upstream diagnosis.

Safety Precautions

Always prioritize safety:

• Disconnect Battery: Disconnect the NEGATIVE (-) battery terminal before performing any electrical work involving wires or terminals to prevent short circuits and sparks.
• Fuel System Pressure: If you need to work on any fuel line, filter, or pump component, you must relieve fuel system pressure properly beforehand to prevent flammable fuel spray.
• Fire Risk: Gasoline vapors are extremely flammable. No smoking. Work in a well-ventilated area. Have a fire extinguisher rated for class B fires nearby.
• Electrical Safety: Avoid contact with live terminals. Do not bypass the relay with jumper wires unless as a very brief diagnostic test and never leave a bypassed relay unattended – this is a serious fire hazard.

Maintaining Your 1999 Taurus's Fuel System Health

A healthy fuel system requires minimal maintenance beyond the relay:

• Follow Fuel Filter Replacement Schedule: Change the fuel filter according to your owner's manual (usually every 30,000-50,000 miles). A clogged filter strains the pump, increases circuit current, and overheats the relay socket.
• Keep Fuel Tank Adequately Filled: Running consistently on a near-empty tank prevents the pump from being submerged and cooled by fuel, shortening pump life. Avoid letting the tank go below 1/4 full regularly.
• Address Electrical System Issues: Promptly fix problems like dimming lights, alternator warnings, or battery issues. Poor overall electrical health stresses all components, including relays.

FAQ: Common Questions About the 1999 Ford Taurus Fuel Pump Relay

• What are the common 1999 Ford Taurus fuel pump relay symptoms?
  The most common symptoms are an engine that cranks but won't start (fuel pump not priming), sudden stalling while driving, engine hesitation or lack of power under load, and the absence of the fuel pump prime sound when turning the key to "ON."
• Where is the fuel pump relay located on a 1999 Ford Taurus?
  It's located in the Central Junction Box (CJB) near the driver's feet under the dashboard. Remove the CJB cover and identify it using the diagram printed on the lid or the box itself. It's usually marked as "Relay 6," "FP Relay," or "Fuel Pump Relay."
• What is the part number for a 1999 Ford Taurus fuel pump relay?
  The Ford Motorcraft OEM part number is DY-986. Common aftermarket equivalents include Standard RY-826, BWD R2283, Bosch 0332019153.
• How much is a 1999 Taurus fuel pump relay?
  Prices vary. OEM Motorcraft typically ranges from $15-$35. Good quality aftermarket relays range from $7-$20.
• Can I replace the fuel pump relay myself?
  Yes. Replacing the relay requires minimal tools (fingers or pliers) and involves locating the CJB, identifying the relay, pulling the old one out, and plugging in the new one. Basic safety steps like disconnecting the battery and following the location steps carefully are important.
• How do I know if it's the relay or the fuel pump?
  The most reliable DIY test is the relay swap test. Swap the fuel pump relay with a known identical, working relay (like the horn relay). If the engine starts normally, the original fuel pump relay is faulty. If the problem persists and you don't hear the fuel pump prime sound, it could be the pump itself, the fuse, wiring, or inertia switch.
• What size fuse is for the fuel pump on a 1999 Taurus?
  Check the CJB fuse diagram. It's typically a 15A or 20A fuse (e.g., fuse #11). Confirm the amperage and location specifically for your vehicle using the diagram.
• Will a bad fuel pump relay throw a code?
  Usually not on a vehicle this age. While a P0230 (Fuel Pump Primary Circuit) code could set, bad relay contacts often don't trigger a code. Don't rely on the absence of a code to rule out a relay problem.
• Why do fuel pump relays fail?
  The primary cause is wear and tear on the internal electrical contacts from years of switching high current to the fuel pump. Heat (from resistance in the circuit or the relay itself), voltage spikes, moisture/corrosion, and vibration contribute to premature failure.
• Where is the inertia switch?
  The inertia fuel shutoff switch is generally located in the passenger side footwell, mounted vertically on the inside of the kick panel or near the toe board. It has a prominent red button on top for resetting if it was tripped (e.g., by hitting a pothole hard).

Conclusion:

A failing fuel pump relay is a frequent cause of debilitating fuel delivery problems in your 1999 Ford Taurus. Recognizing the symptoms – especially the simultaneous crank-no start and lack of fuel pump priming noise – and knowing its location in the Central Junction Box are the first critical steps. A simple relay swap test is often the quickest way to confirm the diagnosis. Replacing the relay is an uncomplicated and inexpensive repair that any owner can usually perform. While the relay is a common point of failure, using a quality replacement part and addressing any underlying wiring or overheating issues will help ensure reliable operation. When dealing with any electrical component related to fuel, always prioritize safety by disconnecting the battery first. By understanding the role and maintenance of this vital switch, you can keep your Taurus running smoothly for years to come.