Replacing The 955I Fuel Pump: A Step-By-Step Guide

The Triumph 955i fuel pump is a component of various Triumph motorcycle models, including the Daytona, Speed Triple, and Tiger. When the fuel pump fails, the bike may experience issues such as a no-start condition or a lack of power. Replacing the fuel pump can be a complex task, as it involves working with electrical systems and fuel lines. It is important to consult a repair manual or seek assistance from a qualified technician to ensure a safe and proper replacement. Additionally, diagnosing the root cause of the fuel pump failure is crucial to prevent recurrence.

Troubleshooting a faulty fuel pump

Part 1: Check if the issue is fuel-related

• Listen for the fuel pump: Put your ear near the fuel tank and turn the ignition key to the "on" position. A properly functioning fuel pump should make an audible low humming noise. If you hear a loud whining sound, it could indicate a problem.
• Whack the fuel tank: Ask an assistant to crank the engine while you hit the fuel tank with a rubber mallet. If the vehicle starts during this step, it suggests that the electric motor inside the pump is faulty.
• Use starter fluid: Caution: This step can be dangerous and may cause personal injury or engine damage. Proceed with caution and ensure you have the necessary safety equipment, such as safety glasses and a fire extinguisher. Attempt to start the vehicle by removing the air intake and spraying starter fluid into the throttle body. If the vehicle starts and runs momentarily, it confirms a fuel-related issue, possibly indicating a bad pump.

Part 2: Advanced tests

• Check the fuel pump electrical circuit: For older continuous-style fuel systems, check the relay that controls the fuel pump via the engine control module (ECM). For newer returnless fuel systems, ensure the fuel pump control module (FPCM) is functioning correctly by verifying the integrity of the wiring in the pump circuit.
• Check the fuel pressure regulator: Returnless fuel systems do not have external pressure regulators. For continuous systems, disconnect the attached vacuum hose and observe whether the pressure increases. If it doesn't, either the regulator is faulty or there is an inadequate vacuum supply.
• Check the fuel filter: Continuous fuel systems have external filters that are relatively easy to install. Rather than testing the filter, consider installing a new one to see if it improves the issue. Remember to relieve the fuel system pressure before replacing the filter for safety.

Part 3: Further tests

• Check fuel pressure and/or volume: Connect a mechanical fuel pressure gauge to the test port on the fuel rail and turn the ignition to the "on" position. Compare the reading to the specification in your repair manual. If the reading deviates significantly, it may indicate a faulty fuel pump.
• Check fuel trim with a scan tool: If your engine is running, use a scan tool to check the short-term fuel trim (STFT). Typically, fuel trim readings should be between -10 and 10, although this may vary for some vehicles. If the fuel trim is above 10, it suggests the engine is running lean, and the fuel pump may not be delivering enough fuel.

If you have identified that your fuel pump is faulty and requires replacement, refer to resources specific to your Triumph 955i motorcycle for detailed instructions.

Buying a replacement fuel pump

When buying a replacement fuel pump, there are a few things to keep in mind. Firstly, it is important to ensure that you are purchasing a compatible fuel pump for your specific vehicle. In this case, you are looking for a fuel pump that is compatible with the Triumph 955i. It is also important to consider the quality and price of the fuel pump.

There are a variety of places where you can purchase a replacement fuel pump. One option is to buy directly from the original equipment manufacturer (OEM). This option may be more expensive, but it can guarantee quality and compatibility. Another option is to purchase from a reputable aftermarket parts supplier. Aftermarket parts can vary in quality, so it is important to do your research and read reviews before making a purchase.

When shopping for a replacement fuel pump, it is important to compare prices and read reviews from other customers. Additionally, it is a good idea to check if there are any recalls or warranties related to the fuel pump. In some cases, you may be covered under a recall or warranty program, which can save you money on the replacement part.

Finally, it is recommended to have a qualified mechanic install the replacement fuel pump. While it is possible to install the fuel pump yourself, it can be a complex and dangerous task due to the high-pressure fuel lines and the risk of fire. A qualified mechanic will have the necessary tools, experience, and safety precautions to properly install the replacement fuel pump.

Some specific fuel pump options that are compatible with the Triumph 955i include:

• Caltric Fuel Pump: This option is available on Amazon and is compatible with the Triumph Daytona 955i from 1998 to 2005. It has received mixed reviews, with some customers reporting that it worked great, while others had issues with the pump failing after a short period of time.
• Denso: According to a forum post, Denso offers a 38mm fuel pump that should work with the Triumph 955i. However, the original poster preferred to find the OE supplier.

Testing the voltage of the pump plug leads

Step 1: Prepare the Settings

Connect a digital multimeter to the positive and negative terminals of the fuel pump. Ensure there are no broken circuits between the fuel pump and relay.

Step 2: Switch Ignition

Insert the key into the ignition and turn it on without starting the engine. You should hear a soft whirl sound from the pump, indicating its readiness to pump fuel. If the pump is functioning, proceed to check if it's receiving sufficient electrical power. A power deficiency may cause the multimeter to show a false voltage reading. To confirm, perform a voltage drop test.

Step 3: Test Negative Terminals

Split the circuit into two parts: the ground phase and the positive phase. Use a jumper wire to power the fuel circuit and energize the pump. Now, connect the multimeter to the negative terminals of both the battery and the pump. Conduct these tests using a live circuit wire. If the meter shows a reading of more than 0.1, it indicates a loss of voltage power. This could be due to damaged harness connectors or poor wiring.

Step 4: Test Positive Terminals

Connect the multimeter to the positive terminals of the pump and the battery. Also, test the output terminal of the fuel pump to ensure it's functioning as expected. If the voltage drop exceeds the recommended reading of 0.1 volts, it confirms that the harness connectors or wiring is faulty. You need to locate the exact fault to rectify the issue.

Step 5: Testing Pump Relay

Locate the fuel pump relay, usually on the dashboard or engine compartment. Remove the relay and have an assistant switch on the ignition without cranking the engine. Check for voltage at the relay connector using the multimeter. Reinstall the relay, then test the fuel pump connector at the rear of the vehicle for incoming voltage using the multimeter.

Step 6: Test the Pump

Remove the fuel pump and place it on a flat surface. Use jumper wires connected to the battery to test for voltage. If removing the pump is challenging, take your battery to the rear of the vehicle and connect the jumper wires to both the battery and fuel pump, being cautious to avoid sparking.

Additionally, here are some general tips and insights on testing voltage:

• Voltage drop testing is crucial for diagnosing fuel pump issues as it compares the voltage at the component to the battery or charging voltage.
• A voltage drop occurs due to resistance in the circuit supplying the pump, which could be in the connectors, grounds, or harness.
• Specialized piercing probes are recommended for piercing the wires to take voltage readings. If you damage a wire, seal the puncture with electrical tape.
• Always address the negative side of the circuit first, followed by the positive side during voltage drop tests.
• During testing, ensure the fuel pump circuit is energized by energizing the fuel pump relay. Typically, fuel pumps run for a few seconds to prime the system until an RPM signal is generated.
• If the negative circuit is healthy, the voltage drop should be 0.5V DC or lower. Higher readings indicate an issue, likely due to damaged vehicle wiring or harness connectors.

Checking the ground connection

To check the ground connection of your 955i fuel pump, you will need to first locate the pump. This can be done by accessing it through the back seat by removing the seat base cushions or by taking out the fuel tank and accessing the pump on top of it.

Once you have located the pump, you will find a connector that sends power to it. This connector should have two thick wires and two thin wires connected to it. The thick wires are for power and ground, while the thin wires are the float or level sensors that send signals to the gauge cluster.

To test the ground connection, you will need a pair of jumper wires and a test light. Connect one of the jumper wires to the power wire and the other to the ground. Then, connect the other ends of the jumper wires to the test light to form a complete circuit. Now, connect the ground wire to the lead end of the test light and the power wire to the tip of the test light.

If the test light lights up, you have good power and ground going to the fuel pump. If the test light doesn't light up, you will need to check for lost power or lost ground.

To check for lost power, connect the lead end of your test light to a good ground and its tip to the power wire. Have someone turn the key on and off. If you have good power, the test light should light up.

To check for lost ground, connect the lead end of the test light to the positive terminal of your car's battery and the test light tip to the ground wire. Turn the ignition key to its on position. If the test light powers up, you have a good ground. If it doesn't, you may have a problem in the circuit.

Additionally, when checking the ground connection, it is important to ensure that the ground wire is connected to a bare metal surface. Paint is not a conductor of electricity, so be sure to sand, grind, or chip away any paint or corrosion from the surface before connecting the ground wire.

Replacing the fuel pump relay

To replace the fuel pump relay, you will need a 10mm spanner to undo the negative battery terminal, a replacement fuel pump relay module, and about 5 minutes of your time.

First, disconnect the negative battery terminal and remove the lid on the fuse box. Next, locate the module and remove it by slipping it out of the grasp of the two clasps on either side. Then, remove the five wire harness heads from the module, taking care not to pull on any of the wires. Once complete, push the wire harness heads into their respective locators on the new module and place the module back into the fuse box. Finally, replace the lid and reconnect the negative battery terminal.

Note that you will get the ESP/BSP warning light on your dashboard because of the disconnection of the battery terminal. To clear it, turn the steering wheel all the way to the left, then all the way to the right, and then centre it.

If you are having trouble removing the relay, it may be corroded in place. Try using contact cleaner as a lubricant and rock it back and forth while pulling. If you are still unable to remove the relay, you may need to use channel locks or similar tools, but be careful not to pull too hard as you can break the relay.

Frequently asked questions