Nissan 100NX N14 silhouetteN14

MECHANICAL FUEL PUMP - Fuel Pump / Operation / Fuel Pressure

EF & EC-176prose procedure

Mechanical fuel pump (carbureted GA13DS/GA14DS/GA16DS models).

Continued from EF & EC-175

Fuel Pump

The fuel pump is a mechanical type and is mounted on the cylinder head. The end of the pump lever rests on the camshaft. When the camshaft rotates, the lever moves in a reciprocating motion to deliver fuel from the fuel tank to the carburetor.

Operation

  1. 1
    Flush pump by immersing it in a fuel bath and operating rocker arm several times.
    Fuel pump illustration with arrows labeled 'Block' (left, into inlet port) and 'Move' (right) on the rocker arm, illustrating the operation test.
    SEF743H
  2. 2
    Drain fuel from fuel pump. Then block off the inlet port and check that pump does not move.
  3. 3
    Remove your finger from the inlet port and listen for a suction sound which will confirm that sufficient suction was produced.
  4. 4
    Block off outlet port and return port. Once again operate rocker arm. After air pressure has been built up, confirm that pressure remains for two or three seconds after.
    Fuel pump illustration with arrows labeled 'Block' (left, outlet/return port), 'Operate' (right, rocker arm) and another 'Block', illustrating the air pressure build-up test.
    SEF744H
  5. 5
    Put a finger over outlet port and again build up pressure in pump. Then submerse pump in a fuel bath and check for air leaks.
    Before starting to work on any part of fuel system, disconnect ground cable from battery. When disconnecting fuel hoses, use a container to catch fuel remaining in hoses.

Fuel Pressure

  1. 1
    Disconnect fuel return hose and plug with a suitable blind plug.
    Fuel pump connected with a pressure gauge for fuel pressure check. Callouts: 'Suitable blind plug', 'Fuel feed outlet hose', 'From fuel filter', 'Fuel feed inlet hose', 'To carburetor'.
    SEF745H
  2. 2
    Disconnect fuel feed outlet hose and connect fuel pressure gauge between fuel pump and carburetor.
  3. 3
    Check fuel pressure with engine running at various speeds. If out of specification, check for fuel filter clogging or improper fuel pump operation.
    Fuel pressure: 20.6 - 34.3 kPa (0.206 - 0.343 bar, 0.21 - 0.35 kg/cm2, 3.0 - 5.0 psi)
Fuel pressure0.206 - 0.343 bar, 0.21 - 0.35 kg/cm2, 3.0 - 5.0 psi; engine running at various speeds
20.6 - 34.3kPa
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