Fig. 4.2 Fuel pump and filter
1. Upper body; 2. Inlet valve cover; 3. Inlet valve spring; 4. Intake valve plate; 5. Exhaust valve seat; 6. Exhaust valve plate; 7. Exhaust valve spring; 8. Exhaust valve stop; 9. Diaphragm; 10. Diaphragm spring; 11. Manual pumping lever; 12. Lower body; 13. Gasket; 14. Pivot axis of the lever; 15. Filter bracket; 16. Filter element; 17. Filter housing; 18. Filter housing seal.
Note: Before you begin, please see the warning in Chapter 1.
Examination
1. To check the fuel pump on the engine, it is necessary to temporarily disconnect the outlet hose from the pump (going to the carburetor).
2. On early models, the fuel pump is equipped with a manual priming lever. To check the serviceability of such a pump, cover the pump outlet with a rag and operate the lever (see illustration).
3. The fuel pump on later models does not have a lever, and to check it, the engine must be turned over with the starter. To prevent the engine from starting, disconnect the high-tension wire from the center of the distributor cap and ground it.
4. When the pump is running, fuel should splash out of its outlet pipe. If the pump is working satisfactorily, connect the fuel line and high-tension wire. If the pump is defective, remove it for inspection or replacement.
Removal
5. Mark the pump inlet and outlet hoses, then loosen the fastening clamps, disconnect the hoses from the pump (see illustration) and seal them.
6. Unscrew the nuts securing the pump to the engine and remove the washers.
7. Remove the fuel lift pump from the engine and remove the seal (see illustration).
8. On a manual fuel pump with a fuel filter, remove the filter from the pump by unscrewing the mounting nut, then remove the filter housing and the filter itself (see illustrations).
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9. The late modification pump cannot be disassembled and must be replaced if faulty. The upper housing can be removed from the early type pump and the diaphragm and the inlet and outlet valves can be inspected. Mark the alignment of the upper and lower pump housings, unscrew the fastening screws and separate the parts.
10. Check the valves on the back of the top cover. If they are suspected of being faulty, the top cover must be replaced. Check the diaphragm and its spring for contamination, and replace them as necessary (see illustrations).
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11. On an early type pump, replace the fuel filter if it is clogged (see Section 1). Also replace the fuel filter housing seal if it is in poor condition (see illustration).
Installation
12. Install in the reverse order of removal. Make sure all mating surfaces are clean and replace the seal. Tighten the pump mounting nuts to the specified torque Specifications.