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Fuel Pump - Electric GMC Cab & Chassis S15

Testing & Diagnostics 1 illustration ~494 words

COMPONENT TESTING

Note. Specific component testing information not available. Refer to any tests performed during REMOVAL & INSTALLATION or OVERHAUL procedures

DESCRIPTION & OPERATION

All 2.5L TBI engine equipped trucks use a low pressure pump with a rated output of 4-13 psi (.28-.91 kg/cm 2 ). The fuel pump is mounted to fuel sending unit in fuel tank.

A relay is used to control fuel pump operation. When ignition is turned on, relay activates fuel pump for about 2 seconds. This activation is used to prime injectors. If electronic pulses from distributor are not received after the 2 second time period, relay shuts fuel pump off.

General Motors

  1. Relieve fuel system pressure by removing "FUEL PUMP" fuse from fuse block. Crank engine. Engine will start and run until fuel remaining in fuel lines is used. After engine stops, crank engine an additional 3 seconds to relieve any remaining pressure. Turn ignition off and install fuel pump fuse.
  2. Connect a fuel hose to throttle body feed line. Route line to a one quart, calibrated container. Apply battery voltage to terminal "G" of Assembly Line Communications Link (ALCL). (Scheme 71) Fuel pump should supply 1/2 pint (240 ml) or more of fuel in 15 seconds.
  3. If fuel supply is okay, pump is operating properly. If fuel supply is not okay, check for restrictions in supply line. Repair or replace line if necessary. If there are no restrictions, perform «FUEL PUMP PRESSURE TEST»(/gmc/cab-chassis-s15/1985-1988/remont/testing-diagnostics/#fuel-pump-electric).

Assembly Line Communications Link Test link is under left side of instrument panel. Scheme 71

Scheme 71: Assembly Line Communications Link Test link is under left side of instrument panel.
Scheme 71: Assembly Line Communications Link Test link is under left side of instrument panel.
  1. Relieve fuel system pressure by removing "FUEL PUMP" fuse from fuse block. Crank engine. Engine will start and run until fuel remaining in fuel lines is used. After engine stops, crank engine an additional 3 seconds to relieve any remaining pressure. Turn ignition off and install fuel pump fuse.
  2. Remove air cleaner. Plug thermal vacuum port on throttle body. Install Fuel Pressure Gauge (J-29548-A) between throttle body and fuel filter. Start vehicle, and note pressure reading. Pressure should be 9-13 psi (.63-.91 kg/cm 2 ).
  3. If pressure is incorrect, check throttle body injection system. Relieve fuel pressure. Remove gauge and connect fuel line. Start engine and check for leaks. Install air cleaner. Remove plug from thermal vacuum port on throttle body.

Removal

  1. Remove "FUEL PUMP" fuse from fuse block. Crank engine. Engine will start and run until fuel remaining in fuel lines is used. After engine stops, crank engine an additional 3 seconds to relieve any remaining pressure. Turn ignition off and install fuel pump fuse.
  2. Disconnect battery negative cable. Raise and support vehicle. Remove fuel tank. Turn sending unit lock ring counterclockwise, and pull lock ring away from tank. Remove fuel pump/sending unit assembly from tank. Remove pump from sending unit.

Installation

Reverse removal procedure. Start engine and check for leaks.

SPECIFICATIONS

Note. Specifications table not available. Refer to specifications within appropriate TESTING subject(s) in this article.

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