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Fuel Pressure

Begin basic diagnosis of fuel system by determining fuel system pressure.

WARNING: ALWAYS relieve fuel pressure before disconnecting any fuel injection-related component. DO NOT  allow fuel to contact engine or electrical components. DO NOT  pinch polyamide fuel pipes closed for any reason. Rubber-lined polyamide pipes CANNOT be bent or clamped without causing permanent damage to pipe.
  1. Remove hot-air guide at left rear of engine compartment. Unscrew and remove cap nut from test connection of fuel distribution line. See Figure . Connect fuel pressure gauge. Catch any spilled fuel with a shop rag.
    CAUTION: DO NOT  allow sealing ball to fall out when removing cap nut.
  2. Disconnect DME relay from fuse/relay block and jump terminals No. 30 and 87b together. See Figure . Fuel pump should operate at specified pressure. See FUEL PUMP PERFORMANCE  . After testing, remove test equipment and tighten cap nut to 108 INCH lbs. (12 N.m).
FUEL PUMP PERFORMANCE

Application Pressure psi (kg/cm2 ) Volume in 30 Sec. Pts. (L)
911 Carrera 2/4 (1) 52-58 (3.6-4.0) 1.8 (.85)
(1) Unregulated pressure (no vacuum applied to pressure regulator). Regulated pressure (vacuum applied to pressure regulator) is 45-51 (3.1-3.5).
NOTE: Digital Motor Electronic (DME) relay terminal numbers are marked on the relay socket.
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