How to Solve High Pressure in Natural Gas Vehicles?
4 Answers
The gas cylinder booster starts working and the gas supply volume can be adjusted within the range of 0.8-1.2Mpa. If the fuel flow rate exceeds a certain limit, the fuel outflow path will be cut off to ensure fuel safety.
I had the same issue with my natural gas vehicle before, it was really scary when the pressure gauge needle shot up to the red zone. Later I learned that the most common cause is a faulty pressure regulator, which is a critical component for controlling gas pressure. Over time, the sealing rings can degrade or the springs can fail, causing it to malfunction. Another less obvious reason is improper operation at the gas station, where high-pressure natural gas is directly rushed into the gas cylinder. It's recommended to immediately shut off the manual valve of the gas cylinder, pull over and turn on the hazard lights. Don't tamper with the pipelines yourself—an experienced technician can use tools to measure the outlet pressure of the regulator to diagnose the issue. For regular maintenance, avoid overtightening the regulator screws, clean the filter element periodically, and always monitor the pressure gauge during refueling to ensure it doesn't exceed 20 MPa. Also, avoid parking the car under direct sunlight in hot weather, as gas expansion can easily lead to uncontrolled pressure.
I've worked on many CNG vehicles. When encountering high pressure, the first thing to check is the pressure regulator. This component is located near the fuel tank under the vehicle, and the three-stage pressure reduction structure has the highest failure probability. Especially in winter, it's common for moisture to freeze and jam the valve core. Use a pressure gauge to measure the first-stage outlet pressure, which should be 1-2 MPa. If it exceeds this range, that's the fault. Some vehicles experience false alarms from pressure sensors, and short circuits caused by damp wiring can also cause false high readings. I usually first check whether the gas cylinder valve is fully open, as operating in a fully closed state with pressure buildup is more dangerous. In emergencies, you can start the engine to consume gas and reduce pressure, but continuous high pressure requires immediate shutdown and repair. For modified vehicles, check the certification, as pipelines modified by non-standard workshops often can't withstand the pressure and are prone to bursting.
Excessive pressure is no trivial matter; I've seen pressure gauges explode. Focus on three main points: Check if the pressure relief valve is frozen or stuck—try pouring hot water on it; see if the gas cylinder's safety valve has failed—if the lead seal is damaged, it must be replaced; and inspect the refueling nozzle's check valve, as debris blockage can cause high-pressure gas backflow. It's normal for pressure to be slightly high right after refueling, but it should drop within minutes of driving. If the high pressure persists, immediately turn off the engine and close the main valve. Get it checked at a certified gas station, as small workshops might have inaccurate equipment. Avoid parking in direct sunlight, and don’t clutter the trunk with items that could press against the gas line. Regular pressure tests are far cheaper than repairs.
