How many amps does a fuel pump take?
On most vehicles, a new fuel pump draws about three to five amperes of current. This amperage or current draw can be measured at the fuel pump fuse located in the vehicle’s fuse box.
What should the voltage be at the fuel pump relay?
You should have 12 volts at the dark green/yellow wire at the fuel pump relay. The inertial fuel shutoff switch is between the relay and the fuel pump. The pink/black wire from the inertial switch to the fuel pump should have 12 volts. You can measure the voltage, on the pink/black wire, at the fuel pump.
How is the current of a fuel pump measured?
The fuel pump current can be measured by inserting an ammeter in series with the fuel pump load circuit at the fuse block and measuring current while the fuel pump is running. A better solution is to use an amp clamp on the positive wire of the fuel pump. This works for vehicles that use a pulse-width modulated voltage supply to the pump.
How does voltage and current affect fuel pump?
Fuel pressure and volume are influenced by voltage, current and the demand controlled by the regulator. If a fuel pump is not receiving the correct voltage, it cannot spin fast enough. Voltage drop testing can isolate problems that can still remain even if the pump is replaced.
Can a voltage drop test be done on a fuel pump?
TESTING VOLTAGE DROPS. A voltage drop test is the only effective way to find excessive resistance in high-amperage fuel pump circuits. With the right leads and back-probes, it’s possible to do the test (if you have access to the top of the tank) without any disassembly.
You should have 12 volts at the dark green/yellow wire at the fuel pump relay. The inertial fuel shutoff switch is between the relay and the fuel pump. The pink/black wire from the inertial switch to the fuel pump should have 12 volts. You can measure the voltage, on the pink/black wire, at the fuel pump.
How does pulse width of fuel pump work?
A module, either the engine control module or a PWM module, determines the desired fuel pressure at the engine and pulses the negative side of the fuel pump circuit to provide the desired amount of fuel. Keep in mind, the pulse width does not change the voltage supplied to the fuel pump – that value remains the same regardless of the duty cycle.
What does it mean when the voltage drops on a fuel pump?
If the voltage drop is greater than the recommended reading of 0.1 volts then this is a confirmation that indeed the harness connectors or the wiring is faulty. You need to locate the exact location of the fault to correct the problem.
Where is the fuel pump voltage test located?
It is located at the back of the vehicle next to or in the fuel tank. It pumps fuel from the tank to the engine. The pump voltage test is important for checking the effectiveness of the fuel pump. Here’s how to perform the test. Connect the digital multimeter to the positive and negative terminals of the fuel pump.