Fuel pump — inspection and repair (VAZ-2108)

Check the fuel supply by the pump. Insufficient filling of the carburetor with fuel may be caused by a faulty fuel pump, as well as clogged or damaged fuel lines and fine fuel filter.

To determine the cause of the malfunction, disconnect the hose from the discharge pipe 1 (see figure 14) and using the lever 8 of the manual fuel pump, check whether fuel is supplied. If fuel is not supplied, disconnect the hose from the inlet pipe 4 and check whether a vacuum is created at the inlet of this pipe. If there is a vacuum, then the fuel lines or fine filter are damaged or clogged. If there is no vacuum, the fuel pump is faulty.

The fuel pump can be tested on a stand. Rotating the drive shaft, which has an eccentricity of 1.25 mm, at a frequency of (2000±40) rpm, check the pump capacity, which should be no less than 1 l/min at 20°C. The discharge pressure at zero fuel supply should be 0.21-0.30 kgf/cm².

In case of malfunction, the pump is disassembled and the condition of the parts is checked. All parts must be washed with gasoline and blown with compressed air. Cracks and breaks in the body parts are unacceptable. Leakage of the inlet and discharge valves is not allowed. The inlet 4 and discharge 1 pipes must not rotate in their seats or have an axial displacement. The diaphragm must not have breaks, peeling or hardening. The filter must be clean and without tears. The sealing edge of the filter along the perimeter must be smooth. The pump valves must not stick.

After checking, all worn parts are replaced with new ones. Damaged pump gaskets are always replaced with new ones and lubricated with a thin layer of grease when installing the pump.