Note: Before you begin, please see the warning in Chapter 1.
Checking the serviceability
1. To check the fuel pump on the engine, temporarily disconnect the outlet pipe that leads to the carburetor, plug the pump outlet with a ball of rags and have an assistant quickly crank the engine with the starter.
Warning. Keep your hands away from the electric fan.
2. The pump can also be checked by removing it. Disconnect the outlet tube from the pump. Prime the pump by manually moving the lever up and down; if the pump is working properly, a strong stream of fuel will spray out of the outlet pipe.
3. If a suitable pressure gauge is available, the test can be performed more accurately. Before connecting the pressure gauge to the fuel system, start the engine and let it idle for a few minutes to completely fill the carburetor float chamber. Stop the engine, disconnect the fuel supply line from the carburetor, and then connect the pressure gauge to it. Use a short transparent tube to make the connection. Using a clamp, clamp the return line to the fuel tank. Holding the pressure gauge as high as possible with the vertical tube, start the engine and let it idle. Slowly lower the gauge until the fuel level in the transparent tube matches the level of the diaphragm of the fuel pump, then check that the static pressure of the pump matches the data given in Specifications (please note that the engine should be idling, but there should be no fuel movement). Check the return tube for blockage. To do this, remove the clamp, the pressure should drop to 0.01-0.02 bar, if the pressure is higher than this, blow out the return hose.
Removal
Note: A new gasket will be required during installation.
4. Disconnect the negative cable from the battery.
5. Mark the fuel pump inlet and outlet hoses, then disconnect and plug them (see illustration).
7.5. Fuel pump and related components:1 - Fuel inlet hose; 2 - Fuel pump; 3 - Fuel outlet hose; 4 - Fuel filter; 5 - Connecting hose; 6 - Steam separator; 7 - Carburetor inlet hose; 8 - Return fuel hose; 9 - Ventilation hose; 10 - Steam accumulation tank; 11 - Clamp; 12 - Vacuum hose (from the collector); 13 - T-shaped connector; 14 - Vacuum hose (to the vacuum capsule of the valve); 15 - Vacuum hose (to the tank); 16 - Vacuum tank.
6. Loosen the nuts or bolts securing the pump to the cylinder block and remove the washers.
7. Remove the fuel pump and remove the gasket.
Installation
8. Install in reverse order, clean the contact surfaces, and install a new gasket. Finally, tighten the nuts/bolts securely.