Introduce how to disassemble and inspect Yanmar marine engine fuel injection pump

 Introduce how to disassemble and inspect Yanmar marine engine fuel injection pump

1，The fuel feed pump pumps fuel from the fuel tank, passes it through the fuel filter element, and supplies it to the fuel injection pump.
The fuel feed pump is mounted on the side of this engine and is driven by the (eccentric) cam of the fuel pump cam-
shaft. It is provided with a manual priming lever so that fuel can be supplied when the engine is stopped.
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2，5-1 Construction of fuel feed pump

1. Bottom body                            8. Lever assembly
2. Piston spring                            9.O-ring
3. Piston                                      10. Stop pin
4. Diaphragm spring                   11. Top body assembly
5. Diaphragm assembly              12. Packing
6. Pin                                           13. Cover
7. Lever return spring                 14. Small screw                                  
                                                   15. Cap
                                               

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3 Disassembly and reassembly of fuel feed pump
3. 1 Disassembly
(1) Remove the fuel feed pump mounting nut, and take the fuel feed pump off the fuel injection pump.
(2) Clean the fuel feed pump assembly with fuel oil.
(3) After checking the orientation of the arrow on the cover, make match marks on the upper body and cover, remove the small screw, and disassemble the cover, upper body and lower body.
4. Reassembly
(1) Clean all parts with fuel oil, inspect, and replace any defective parts.
(2) Replace any packings on parts that have been disassembled.
(3) Make sure that the intake valve and discharge vaive on upper body are mounted in the proper direction, and that you don't forget the valve packing.
(4) Assemble the diaphragm into the body, making sure the diaphragm mounting holes are lined up (do not force).
(5) Align the match marks on the upper body of the pump and cover, and tighten the small screws evenly.

5， Fuel feed pump inspection
(1) Place the fuel feed pump in kerosene, cover the dis charge port with your finger, move the priming lever and check for air bubbles (Repair or replace any part which emits air bubbles).

(2) Attach a vinyl hose to the fuel feed pump intake, keep the pump at the specified depth from the fuel oil surface, move the priming lever by hand and check for sudden spurts of fuel oil from the discharge port. If oif is not spurted out, inspect the diaphragm and diaphragm spring and repair/replace as necessary.
(3) Diaphragm inspection Parts of the diaphragm that are repeatedly burned wifl become thinner or deteriorate over a long period of time.
Check the diaphragm and replace if necessary.

(4) Valve contact/mounting Clean the valve seat and vaive with air to remove any foreign matter.

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(5) Inspect the diaphragm spring and piston spring for sett!-
ing and the piston for wear, and replace as necessary.
NOTE: Replace parts as an assembly.