What is the normal voltage for a car fuel pump?
3 Answers
The normal voltage for a car fuel pump is between 300 and 350 kpa. The symptoms of low fuel pump pressure and the method to check the fuel pump pressure are as follows: Symptoms of low fuel pump pressure: Difficulty starting the engine, insufficient driving power, sudden stalling, jerking when accelerating sharply, engine warning light on, engine shaking, and abnormal noises while driving. Method to check fuel pump pressure: Turn on the ignition switch without starting the vehicle, unplug the fuel pump relay, use a dedicated jumper wire to connect the fuel pump circuit, start the vehicle, and then connect a fuel pressure gauge to check the engine's fuel pressure value.
I usually enjoy tinkering with cars and have found that the fuel pump operates normally within a voltage range of 12 to 14 volts. The car is powered by a 12-volt battery, and after starting, the alternator raises the voltage to 13-14 volts, allowing the fuel pump to run steadily within this range. If the voltage drops too low, say to 11 volts or less, the fuel pump's speed will decrease, leading to insufficient fuel supply, which can cause the engine to shake or have difficulty starting. Common issues include an aging battery, corroded wiring contacts, or a faulty relay. It's advisable to use a multimeter to measure the voltage by turning the key to the ON position without starting the car and then testing the fuel pump wires. Regular checks of the electrical system can prevent problems—don't underestimate the importance of these small details.
After decades of driving, I believe the normal voltage for a fuel pump should be around 12 to 14 volts. I once encountered a car that wouldn't start, and upon checking, the voltage was only 10 volts, causing the fuel pump to operate poorly. This happens because a car battery typically provides 12 volts, and after starting, the alternator maintains higher voltage. Low voltage can lead to increased fuel consumption or even cause the engine to stall midway, which is quite dangerous. I recommend having mechanics check the electrical circuit during routine maintenance, paying special attention to corroded wire connections, as older cars are prone to this issue. If problems arise, simply replacing the fuel pump or a fuse can solve it, saving both money and hassle.
