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Home >> Porsche >> 1987 >> 944 Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> DME Control System >> Diagnosis & Testing >> Fuel Pressure
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Fuel Pressure

  1. Locate fuel pipe cap nut at end of fuel rail (left side on 911 Carrera). Remove cap being careful that sealing ball does not fall out. Connect a Test Pressure Gauge (P 378).
  2. Start engine and maintain idle speed. Pressure gauge should show 29.4 psi (2.06 kg/cm2 ). Disconnect vacuum line at pressure regulator. Pressure gauge should show 33.8-39.7 psi (2.37-2.78 kg/cm2 ).
  3. Pinch fuel return line of pressure regulator. Pressure gauge should show a minimum of 59.0 psi (4.13 kg/cm2 ). If fuel pump does not meet specifications, check fuel filter or replace fuel pump and retest.
  4. If engine will not start, check fuse No. 2. If good, remove DME relay (911 Carrera), or fuel pump relay "U" (924S and 944) and bridge terminals No. 30 and 87b. Pressure gauge should show 33.8-39.7 psi (2.37-2.78 kg/cm2 ).
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