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.

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.
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.