What is the normal fuel tank pressure?
2 Answers
The fuel pump pressure should be 284-325kpa. The following is a related introduction about the fuel tank: 1. Function: In addition to storing fuel, the fuel tank also plays roles in heat dissipation, separating air bubbles in the fuel, and settling impurities in the hydraulic system. There are two types of fuel tanks: open tanks and closed tanks. Open tanks have a simple structure and are easy to install and maintain, making them commonly used in hydraulic systems; closed tanks are generally used for pressurized fuel tanks. 2. Structure: The fuel tank usually has two outlets: one is the fuel filler neck that is directly visible, and the other is used to install the fuel pump and fuel metering device. The fuel tank is a relatively sealed system, often equipped with ventilation devices to prevent deformation caused by excessive fuel consumption and the resulting pressure difference between the tank and the atmosphere. Early fuel tanks were mostly made of metal materials, but later, synthetic materials were increasingly used to meet the requirements of lightweight and structural design.
I've been repairing cars for many years. Normally, the fuel tank pressure should remain close to zero when the vehicle is parked, which means at atmospheric pressure level. This is because modern vehicles are equipped with an EVAP system specifically designed to control vapor emissions and prevent fuel tank pressure from being too high or too low, which could lead to fuel leaks or malfunctions. The common standard is around 0 psig, and minor fluctuations are acceptable. If the pressure is abnormal, such as being too high, it's likely due to a loose fuel cap or a blocked vent line—issues often encountered during annual inspections. I remember once working on a car where the pressure reading was too negative, and it turned out the charcoal canister was faulty; replacing it solved the problem. When car owners perform their own checks, they should pay attention to the fuel cap seal to ensure it hasn't aged. It's also important to regularly visit a 4S shop to have the pressure tested with professional tools, as this is crucial for maintaining vehicle performance and safety. After all, uncontrolled pressure can trigger warning lights and affect driving. I recommend testing the pressure during annual maintenance—it's not expensive.
