Checking and repairing the fuel pump (VAZ-1111)

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.

To determine the fault, disconnect the hose from the discharge pipe 5 (see figure 16) and using lever 12, manually pump the fuel to check whether fuel is supplied. If fuel is not supplied, disconnect the hose from the inlet pipe 8 and check whether a vacuum is created at the inlet of this pipe. If there is a vacuum, then the fuel line or hoses are damaged or clogged. If there is no vacuum, the fuel pump is faulty.

The fuel pump can be tested on a bench. By rotating the drive shaft, which has an eccentricity of 1.25 mm, at a frequency of (2000 + 40) min⁻¹, check the pump capacity, which must be at least 50 l/h at 20°C. The discharge pressure at zero fuel supply must be 0.021-0.03 MPa. In case of a malfunction, disassemble the pump and check the condition of the parts. All parts must be washed with gasoline and blown out with compressed air. Cracks and breaks in the body parts are unacceptable. Leakage of the inlet and discharge valves is not allowed. Inlet 8 and discharge 5 pipes must not rotate in their seats or have axial displacement. The diaphragm must not have ruptures, peeling or hardening. The filter must be clean and without ruptures. The filter sealing edge should be smooth around the perimeter. The valves should 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.

(The information is published on the website VAZbook)