1. The main function of the fuel filter is to filter impurities in the gasoline, so that the fuel entering the engine for combustion is clean, the combustion is more complete, the formation of carbon deposits in the cylinder is reduced, and the power input is better;
2. If the fuel filter is not replaced for a long time, the filter element inside the fuel filter will be too dirty to filter;
3. In serious cases, the gasoline will be blocked, and the vehicle will not start or stop running, so the gasoline filter needs to be replaced regularly;
4. There are two types of fuel filters for vehicles, one is the built-in fuel filter and the other is the external fuel filter.

This is caused by high pressure oil mercury pressure relief and low oil pressure
The reasons are:
1. The diesel filter is too dirty and blocked, and the vehicle cannot be refueled due to insufficient fuel supply.
2. The fuel injection nozzle is blocked, and the vehicle cannot be refueled due to insufficient fuel intake.
3. The high pressure oil pump relieves pressure, and the oil pressure is too low to add oil.
4. The air filter is too dirty and blocked, the air intake is insufficient, and the combustion is poor, causing the vehicle to be unable to fill with oil.

The solution could be:
1. After the diesel filter is replaced, the problem of smooth oil supply is solved.
2. After cleaning or replacing the fuel injection nozzle, the problem of smooth fuel supply is solved.
3. After maintenance and correction of the high-pressure oil pump, the oil supply pressure reaches the standard and the fault is solved smoothly.
4. After the air filter is replaced, the problem that the intake air is fully combusted normally is solved.