Replacing The Fuel Pump: Step-By-Step Guide For 955I Engines

The fuel pump in a Triumph 955i motorcycle can be challenging to replace. The process involves removing the seats, battery, and various bolts and plastics. It is also important to disconnect the fuel pump and fuel line connections before lifting the tank. While some have opted to replace the fuel pump with a generic alternative, others have chosen to purchase a new one. In addition to the fuel pump, the fuel filter and fuel level sensor may also need to be replaced.

Check for 12V at the pump

To check for 12V at the pump, you will need a digital multimeter. This is a tool that measures the voltage and current in an electrical circuit. Connect the multimeter to the positive and negative terminals of the fuel pump. Ensure there are no broken circuits anywhere between the fuel pump and relay.

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 that it is ready to pump fuel into the engine. If the pump is functioning, find out if it is receiving enough electrical power. A deficiency in power supply may cause the digital multimeter to indicate a false voltage reading at the pump. To confirm the reading, perform a voltage drop test.

Split the circuit into two, with the ground phase on one side and the positive on the other. Use a jumper wire to power the fuel circuit and energize the pump. Connect the digital multimeter to the battery and the pump, both on their negative terminals. Conduct the tests using a live circuit wire. If the meter indicates a reading of more than 0.1, this indicates a loss of voltage power. The reason for the loss could be damaged harness connectors or poor wiring.

Next, connect the digital multimeter to the positive terminals of the pump and the battery. Also, test the output terminal of the fuel pump to see if it is functioning as expected. If the voltage drop is greater than the recommended reading of 0.1 volts, this confirms that the harness connectors or the wiring is faulty. You will need to locate the exact location of the fault to correct the problem.

Finally, establish the location of the fuel pump relay on the dashboard or the engine compartment. Remove the relay and have someone switch on the ignition without starting the engine. Check for voltage at the relay connector using a digital multimeter. Replace the relay and test the fuel pump connector at the back of the car, testing for incoming voltage using the multimeter.

Check the voltage across the pump plug leads

To check the voltage across the pump plug leads, you will need to use a digital multimeter. This will allow you to measure the voltage across the pump plug leads. Here is a step-by-step guide:

• Put on safety glasses to protect your eyes.
• Set the multimeter to 20 volts DC scale, or simply DC if your multimeter has auto-ranging capabilities.
• Connect the positive probe of the multimeter to the positive terminal of the battery.
• With the fuel pump wire harness connected to the fuel pump, connect the negative probe of the multimeter to the power feed wire at the fuel pump connector.
• Turn the ignition to the "on" position. The pump will run for about two seconds while the relay is in prime position, or until it gets an RPM signal.
• Read the voltage on the multimeter. The reading should be less than 0.2 volts. If it is greater, there may be resistance in the power supply circuit for the fuel pump.
• Now, to test the ground side, follow a similar process. Set the multimeter to 20 volts DC scale, or DC if your multimeter has auto-ranging capabilities.
• Connect the positive probe of the multimeter to the ground terminal of the fuel pump connector. Ensure that the fuel pump wire harness is connected to the fuel pump.
• Connect the negative probe of the multimeter to the negative terminal of the battery.
• Again, turn the ignition to the "on" position. The pump will run for a few seconds or until it gets an RPM signal.
• Read the voltage on the multimeter. It should be less than 0.2 volts DC. If it is greater, check for resistance in the ground supply circuit for the fuel pump.

By following these steps, you can effectively check the voltage across the pump plug leads and diagnose any potential issues with the fuel pump circuit.

Check the pump is grounded correctly

To check that the fuel pump is grounded correctly, you will need to use a multimeter. Place one pin of the multimeter on the pump ground and the other on the battery positive. If you do not get a reading, you have a bad ground. Check the ground line for continuity.

• Locate the fuel pump: The fuel pump is typically located inside the fuel tank or close to it. Refer to your vehicle manual for guidance.
• Identify the ground wire: The fuel pump will have a ground wire that needs to be connected to the vehicle's chassis. This wire is essential for establishing a solid electrical connection.
• Clean the ground connection: Ensure that the area where the ground wire will make contact with the chassis is clean and free from debris. A clean surface will ensure a reliable ground.
• Connect the ground wire: Attach the ground wire securely to the chassis using a bolt or screw. Ensure it is tightly fastened to establish a good electrical connection.

By following these steps, you can ensure that the fuel pump is grounded correctly, which is crucial for optimal fuel pump performance and reliability.

Check the relay is operating normally

To check if the relay is operating normally, you can perform a continuity test. This can be done by using a multimeter. Place the probes on the fuel pump terminals and set the multimeter to the continuity setting. If the multimeter beeps, the relay is operating correctly. If the multimeter does not beep, the relay needs to be changed.

Another way to check the fuel pump relay is to perform a voltage test. Set the multimeter to the voltage setting and place the probes on the fuel pump terminals. The voltage must match the voltage of the battery. If the voltage is less than that of the battery, the relay needs to be replaced.

Additionally, you can perform a visual inspection of the fuel pump relay. Remove the relay from the fuse box and look for any visible signs of damage, such as corrosion, burns, or cracks. If you notice any damage, replace the relay.

Check the fuse

Checking the fuse on your 955i is a crucial step in diagnosing any issues with the fuel pump. Here is a detailed guide on how to check the fuse:

Locate the Fuse Box: The fuse box on your 955i is located under the seat. Remove the seat to access the fuse box.

Identify the Correct Fuse: The fuel pump is powered through relay 33 (fuel pump relay) and fuse 8. Locate fuse 8 in the fuse box.

Test the Fuel Pump Relay: With the ignition turned on, check if there is 12V at the relay contact on the fuse side. If you don't get 12V, it could be due to a blown fuse, a corroded fuse holder, a faulty wire, or a corroded relay socket.

Check the Relay Coil: Ensure that the relay coil is receiving 12V. If it's not, check the line and relay connector for any issues.

Listen for the Fuel Pump Priming: Turn the key to the "on" position and listen for the fuel pump to prime. If the fuel pump is not priming, there may be an issue with the relay or the wiring.

Inspect the Wiring: Carefully inspect the wiring for any signs of corrosion or damage. Pay close attention to the wires connecting the relay to the fuel pump and the ECU.

Multimeter Voltage Check: Place one pin of the multimeter on the pump ground and the other on the battery positive terminal. If you don't get a reading, there may be a bad ground or a break in the ground wire.

ECU Ground Check: Check if the ECU is properly grounding the fuel pump. Connect the negative pin of the multimeter to the pump ground and the positive pin to the battery positive terminal. Turn the key to the "on" position and check for battery voltage. If you don't get a reading, there may be an issue with the ECU or a corroded pin in the ECU connector.

Remember to perform these checks in the order listed. After each step, try to prime the fuel pump by turning the key. If the pump still doesn't prime, move on to the next step.

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