Fuel Pump Chevrolet Cavalier I

COMPONENT TESTING

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

DESCRIPTION

Two types of fuel pumps are currently used. Most gasoline vehicles use an engine-mounted mechanical pump. General Motors diesel models also use a mechanical pump to supply fuel to the injector pump. Vehicles with fuel injection use an electric pump. General Motors models use a low pressure (8-14 psi) pump.

Vehicle manufacturers recommend that the pump be replaced as an assembly if found defective. Check pumps for fuel pressure, volume, and vacuum (suction). DO NOT attempt to overhaul or repair pump assembly. Some pumps will have an extra connection for fuel and vapor return to aid in hot starting and prevention of vapor lock.

TESTING

If a complaint is diagnosed as a fuel supply problem, fuel pump, lines, and tank must be tested or inspected before replacing fuel pump. Make the following tests and inspections

Note. For electric fuel pump testing procedures, see the appropriate Fuel Injection article in this section.

FUEL LINES & HOSES

Inspect all metal fuel lines for damage from vibration, impact, or kinking. Inspect rubber hoses for cracks, kinks, or deterioration. Remove fuel tank cap, disconnect fuel line at inlet side of fuel pump, and blow lines clear with compressed air. Also clean tank vent lines.

FILTERS & SCREENS

Inspect and clean (or replace) all filters and screens in both pump inlet and outlet lines and at carburetor/throttle body. In some cases, fuel tank pick-up screen can be clogged enough to affect fuel delivery at high speed.

Mechanical

1. Be sure there is gasoline in the tank. Disconnect ignition wire from distributor.
2. Disconnect fuel line at carburetor inlet fitting. Install length of fuel resistant hose over end of fuel line. Place end of hose into a gasoline container.
3. Crank engine. Compare amount of fuel pumped to specifications for each manufacturer. Pump output should be about 1 pint in 30 seconds.
4. If little or no gasoline flows from hose, check fuel lines or gas tank filter for kinks or restrictions. If lines and filter are clear, pump is defective and must be replaced.

Electrical

1. Disconnect fuel line from carburetor. Install a "T" connector with a pressure gauge in the line and reconnect line to carburetor. Hold pressure gauge about 16" above fuel pump. Pinch off fuel return line (if equipped). Start engine and observe pressure.
2. On General Motors (Corvette) Cross Fire System, plug Thermac vacuum port on TBI. Remove steel line between TBI's and install a pressure gauge using a "T" connector.
3. Start engine and observe pressure. After pressure check, reconnect steel line. If pressure is not within specifications or varies greatly, replace fuel pump.

1. Disconnect fuel line from carburetor. Connect line to a pressure gauge. Hold gauge about 16" above pump level. Pinch off fuel return line (if equipped).
2. Start engine and allow to idle (using gas in carburetor bowl). Observe pressure gauge. Pressure should be about 4-7 psi (.28-.49 kg/cm 2 ) for 4 and 6 cylinder engines, and about 6-9 psi (.42-.63 kg/cm 2 ) for V8 engines.
3. Replace pump if pressure is too high or low, or if pressure varies greatly with the engine speed.

1. Reconnect fuel line to carburetor inlet and check for leaks. Disconnect hose at inlet side of fuel pump. Raise end of hose so fuel will not run out. Connect vacuum gauge to pump inlet with short length of hose.
2. Start engine and allow to idle. Check vacuum level. Gauge should read at least 15 in. Hg. If not, replace pump.

SPECIFICATIONS

FUEL PUMP SPECIFICATIONS (TYPICAL)