The fuel pump of the electric injection system of motorcycle is an important part of the fuel supply. The performance of the fuel pump directly affects the normal power output of the electric injection motorcycle engine. Today, we will talk about the fuel supply component of the electric injection system -- the maintenance and fault analysis of the fuel pump.

First, classification and structure of gasoline pump

Electric spray motorcycle set environmental protection, fuel saving, good start and other advantages in one, deeply loved by the people. Nowadays, the electric injection motorcycle has gradually replaced the motorcycle in the carburetor era. The fuel pump of the electric injection system of the motorcycle serves as an important part of the fuel supply system, which provides the high pressure fuel required by the electric injection system.

The fuel pump structure can be divided into two kinds according to the location of the installation: one is the external type, the fuel pump assembly is set outside the tank, such as the 2008 SUZUKI Falcon fuel pump, this old fuel pump due to its bad heat dissipation conditions, large volume, heavy weight has been eliminated from use, belongs to the past. Instead is now used quite widely reliable, lightweight fuel pump, is the built-in fuel pump. The fuel pump is placed in the gasoline tank of the motorcycle. It uses the gasoline liquid in the tank to cool the heat of the fuel pump, so that the fuel pump can work for a long time and ensure the normal operation of the engine. At present, both pedal, straddle, domestic and imported motorcycles use built-in fuel pump work.

Harley Fuel pump assembly structure drawing: filter, fuel pump, pressure relief valve, internal pipeline wiring harness

Two, the structure and working principle of gasoline pump

Motorcycle electric fuel pump is mainly composed of pump body, permanent magnet motor and shell three parts. After the permanent magnet motor is energized, it will drive the impeller of the pump body to rotate, and the fuel will be sucked from the oil inlet, through the fuel pump, and then pressed out from the oil outlet, to supply pressure fuel for the fuel system.

Fuel pump assembly and throttle assembly oil circuit structure drawing

When the fuel flows through the fuel pump, it also has a cooling effect on the armature of the permanent magnet motor. Because the fuel pump motor is immersed in the fuel tank and there is no air, it is impossible to have a fire when the fuel pump works. The motor of the fuel pump has a permanent magnet fixed to the housing, which is used to generate an electromagnetic force. The base of the gasoline pump assembly consists of a fuel pump power supply, a fuel sensor plug harness, a socket and a fuel output interface.

There is no pressure in the gasoline tank of the motorcycle. Only when the ignition switch is turned on and the vehicle power is switched on, the electric injection system of the motorcycle realizes self-test in the first time. The ECU provides the initial power to the relay of the fuel pump. The fuel tank emits an alternating sound of the fuel pump motor working (indicating that the fuel pump is working). The gasoline in the fuel tank passes through the coarse filter screen of the fuel pump. First, the impurities and large particles of the fuel are filtered out to avoid the impurities entering the fuel pump body and damaging the impeller. The fuel enters the fuel pump motor, and with the operation of the motor impeller, the fuel is compressed and output 4-7kg or even higher pressure of fuel. This pressure value is the designer's allowance to consider the fuel pump motor with long working process, the pump core wear will lead to premature decline of fuel pressure. The pumped fuel passes through the secondary filter element to further filter the fine particles in the fuel and protect the nozzle in the electric injection system from fouling. The filtered fuel enters the pressure relief chamber all the way through the pressure relief valve for pressure relief, to ensure that after pressure relief, the oil pressure of the fuel entering the fuel injection system is always within the range of 3-3.5kg. After pressure relief, excess fuel is returned to the tank.

Appearance of fuel pump with primary coarse filter

After pressure relief, the fuel pressure is kept in the range of 3-3.5kg. The pressure fuel is sent to the injector by the high-pressure oil pipe, and injected by the ECU according to the requirements of the engine working condition. On the fuel pump assembly, there are two fuel filters, one is the primary coarse filter, usually visible appearance, it is installed in the gasoline pump inlet plastic mesh shape of the filter. The other screen is the secondary screen, designed to be placed in the fuel pump assembly plastic parts inside the oil circuit, the secondary screen is designed to protect the electric nozzle, avoid the electric nozzle by fine particles blocked, and affect the spray atomization function. The secondary filter screen is similar to the air filter paper stacked together, the role is to ensure that the fuel filter clean.

Three, the failure of the gasoline pump

The fuel pump of motorcycle electric injection system will cause the following faults in daily use:

1. Due to the long use time of motorcycles, the quality of gasoline in the use of filling does not meet the requirements, or the frequent use of filling with low grade gasoline, resulting in gasoline pump primary and secondary fuel filter blocking, fuel flow decline resulting in insufficient fuel in and out, so that the fuel output pressure is reduced.

2. The failure of the fuel pump of the fuel system, the motor damage of the fuel pump (the fuel level of the tank is too low to work for a long time, the fuel must be replenled in time, otherwise it is easy to burn the fuel pump), and the serious wear of the fuel pump impeller cause the drop of the output fuel pressure of the fuel pump.

3. In the process of disassembling and assembling the gasoline pump in maintenance, the sealing ring of the oil pump and the sealing ring of the oil drain valve are not assembled in place, or the O-ring is damaged by the assembly, resulting in the decrease of fuel pressure in the work of the gasoline pump.

4, fuel supply system circuit caused by failure, power supply is not in place (fuse blown, oil pump lead plug is not in place or open, plug-in contact is poor) or fuel relay fault.

5. The pressure relief valve in the fuel pump assembly fails, which is caused by excess pressure relief.

6, due to the motorcycle has been a long time, or long-term storage, fuel tank corrosion, fuel tank internal processing technology is not good, cause the fuel tank inner wall corrosion, corrosion and blockage of the oil filter, gasoline supply, resulting in fuel pump fuel pressure is insufficient.

7. The oil pump output tubing and the oil tank output interface of the gasoline pump assembly in the fuel tank are broken (such as the old golden Wing, some Harley and some Ducati models), and the oil leakage causes the fuel pressure to drop, resulting in the engine is difficult to start, the engine works abnormally or even cannot start.

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