What Is a Coil Pump?

Fuel pump is a buzzword for the auto parts industry. It is one of the basic components of the fuel injection system of the EFI vehicle. It is located inside the fuel tank of the vehicle. The fuel pump works when the engine is started and the engine is running. If the engine is stopped and the ignition switch is still ON, the HFM-SFI control module turns off the fuel pump power. To avoid accidental ignition.

The fuel pump delivers high-pressure fuel to the manifold, ensuring continuous fuel supply to the injectors.

The fuel pump consists of an electric motor, a pressure limiter, and a check valve. The electric motor actually works in the fuel in the casing of the oil pump. Don't worry because there is nothing in the casing that can ignite. The fuel can lubricate and cool the fuel motor. A check valve is installed at each end, and the pressure limiter is located on the pressure side of the oil pump casing, and has a channel leading to the oil inlet.

ZYB ignition boost fuel pump is suitable for conveying

In some aircraft, the electric centrifugal booster pump is used as an auxiliary fuel pump for the fuel system. The motor is usually mounted on a spar corresponding to the lower position of the fuel tank, while the pump body is immersed in fuel at the bottom of the fuel tank. Take sealing measures between the pump impeller and the motor to prevent fuel or oil vapor from leaking into the motor. When the fuel enters the pump body, a high-speed rotating impeller throws the fuel outward in the radial direction, generating centrifugal force, increasing the fuel pressure, and delivering the fuel to the system. The rotary agitation of the pump also has the effect of separating air and oil vapor from the fuel, so that the fuel supplied to the engine is free of oil vapor.

Due to the higher cost of electric centrifugal booster pumps, the fuel systems of many small lower single-wing aircraft use electric plunger pumps as auxiliary fuel pumps for the fuel system. Plunger pumps are usually installed in parallel with engine-driven diaphragm fuel pumps so that they supply fuel to the engine individually or together.

The plunger type fuel pump is a pulsation pump, which is composed of a solenoid coil, a plunger, a calibration spring, and two one-way valves (net 9-14). The electromagnetic coil is wound on a brass tube connected to two oil chambers. The spring force of the calibration spring pushes the plunger up, and the coil electromagnetic force pushes the plunger down. One one-way valve is installed in the middle of the plunger part, and the other is installed in the middle of the bottom of the brass pipe extension in the oil inlet cavity.

The figure below shows the working principle of a typical vane fuel pump. Four steel blades slide along the radial direction of the rotor in a chute formed on the rotor. One end of the blade is pressed against the inner wall of the pump barrel, and the other end is in contact with the floating shaft through a spring. The internal cavity of the rotor is divided into 4 working chambers by the blades and the floating shaft. The pump barrel is fixed on the casing of the pump, and there are oil inlet and outlet on both sides. The power of the rotor can be engine-driven or motor-driven.

Some hard faults (such as inoperability) that occur in automobile fuel pumps are easier to judge, but some intermittent soft faults that appear are harder to judge. In this regard, the method of detecting the working current of the fuel pump by the automobile digital multimeter can be used to judge its performance. The specific method is as follows.

(1) Put the car digital multimeter in the current block, press the function key (SELECT) to adjust to the DC block, and then connect the two test leads in series to the connection line of the fuel pump being tested.

(2) Start the engine. When the fuel pump is working, press the dynamic record key (MAX / MIN) of the digital multimeter of the car to automatically record the maximum and minimum current of the fuel pump when it is working. By comparing the detected data with normal values, the cause of the failure can be determined. ^[2]

1.Old fuel pump

When troubleshooting the fuel pumps of vehicles that have been used for a long time, such fuel pumps cannot be tested dry. Because when the fuel pump is removed, because there is fuel remaining in the pump casing, when the electric test is conducted, once the contact between the brush and the commutator is not good, sparks will be generated to ignite the fuel in the pump casing and cause an explosion. Very serious.

2.New fuel pump

Newly replaced fuel pumps must not be tested dry. Because the oil pump motor is sealed in the pump casing, the heat generated by the current cannot be dissipated during the dry test, and the motor will be burned as soon as the armature is overheated, so the fuel pump must be immersed in the fuel for testing.

3.Other aspects

After the fuel pump leaves the fuel tank, wipe the fuel pump clean in time, avoid sparks near its placement, and follow the safety principle of "connect first, then power on". ^[2]