GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Prizm 🢒 Engine 🢒 Engine Controls - 1.8L 🢒 Fuel System Diagnosis

Object Number: 245480 Size: MF
(1)Fuel Pressure Gauge Adapter J 42982
(2)Fuel Feed Pipe
(3)Fuel Sender Assembly
(4)Fuel Tank
(5)Fuel Pressure Regulator
(6)Fuel Pump
(7)Fuel Sender (gauge)
(8)Fuel Filter
(9)Pinch Off Area
(10)Fuel Pressure Gauge J 34730-1A
(11)Fuel Injectors
(12)Fuel Rail

System Description

The fuel supply system is a returnless design that has most of the fuel system components located inside of the fuel tank. When the ignition switch is turned to the START position (engine cranking), the circuit opening relay will be energized in order to allow the fuel pump to operate and pressurize the system. The fuel pump will continue to operate if the powertrain control module (PCM) receives a reference signal when the engine is started. The fuel pump operates as long as the circuit opening relay is energized by the PCM. When the circuit opening relay is de-energized, the fuel pump will stop operating. The fuel pump delivers fuel to the fuel rail at high pressure. The fuel pressure regulator, located in the fuel tank, is responsible for keeping the fuel pressure at 301-347 kPa (44-50 psi).

Diagnostic Aids

Check that the fuel pressure regulator has not come loose or is miss positioned. This may cause a low fuel pressure condition.

Check for leakage around all fuel hose/pipe connections. A plugged fuel injector could be the cause of a hard/no-start condition or loss of power.

Erratic fuel pressure may be caused by a fault in the fuel pump electrical circuit. Inspect the wiring harness and components for any of the following conditions:

    • Backed out terminals.
    • Improper mating of terminals.
    • Broken electrical connectors locks.
    • Improperly formed or damaged terminals
    • Faulty terminal to wire connections.
    • Physical damage to the wiring harness.
    • A broken wire inside the insulation.
    • Corrosion of electrical connections, splices, or terminals.

Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

  1. The OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

    2.

  2. This step checks the fuel pump for a worn bearing or a binding impellor. The pump should have a smooth and steady low humming sound. A loud humming or growling noise may indicate a faulty fuel pump. Check a known good vehicle in order to compare pump operation.

    3.

  3. The fuel system can not maintain constant fuel pressure with a leak in any of the following areas:

    • The fuel pump check valve
    • The valve or valve seat within the fuel pressure regulator
    • The fuel injectors

  1. This step checks whether the fuel system is leaking between the fuel pressure gauge and the fuel injectors or between the fuel pressure gauge and the fuel sender assembly.

    2.

  2. This step checks for additional conditions that can cause low fuel pressure other than a faulty fuel pump. Check for any restrictions or blockage in the fuel feed lines and hoses, including those inside the fuel tank. Check the fuel pump electrical circuit for excessive resistance. Proper fuel pump operation requires correct voltage and adequate current flow.

    3.

  3. Check for rust and other foreign materials in the fuel tank. Clean or replace as necessary.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Turn OFF the ignition.
  2. Relieve the fuel pressure. Refer to Fuel Pressure Relief .
  3. Install a fuel pressure gauge. Refer to Fuel Pressure Gage Installation and Removal .
  4. Install a scan tool.
  5. Turn ON the ignition, leaving the engine OFF.
  6. Select Fuel Pump in the Engine Output Controls menu of the scan tool.
  7. Turn ON the fuel pump, using the scan tool.
  8. Observe the fuel pressure indicated by the fuel pressure gauge with the fuel pump running.

Was there any fuel pressure indicated?

--

Go to Step 3

Go to Step 5

3
  1. Turn ON the fuel pump, using the scan tool.
  2. Observe the fuel pressure indicated by the fuel pressure gauge with the fuel pump running.

Is the fuel pressure within the specified value?

301-347 kPa

(44-50 psi)

Go to Step 12

Go to Step 4

4

Is the fuel pressure above the specified value?

347 kPa (50 psi)

Go to Step 22

Go to Step 6

5

Was the circuit opening (fuel pump) relay diagnostic table performed?

--

Go to Step 24

Go to Fuel System - Circuit Opening Relay Diagnosis

6

  1. Remove the bottom cushion of the rear seat in order to gain access to the fuel sender assembly access panel.
  2. Turn ON the ignition, leaving the engine OFF.
  3. Place a listening device against the fuel sender assembly access panel.
  4. Command the fuel pump ON with the scan tool.
  5. Listen for audible fuel pump operation. The fuel pump should have a smooth and steady low humming sound.

Is the fuel pump operating as described?

--

Go to Step 7

Go to Step 24

7

Measure the resistance of the fuel pump, with a DMM.

Is the fuel pump resistance within the specified value?

0.2-3.0 ohms at 20°C (68°F)

Go to Step 8

Go to Step 24

8
  1. Visually and physically inspect the fuel feed pipe for the following conditions:
    2. • Kinks
    • Cracks
    • Incorrect routing
    • Restrictions
  2. Repair as necessary.

Was a repair necessary?

--

Go to Step 25

Go to Step 9

9
  1. Remove the fuel sender assembly. Refer to Fuel Sender Assembly Replacement .
  2. Visually and physically inspect the fuel pump strainer for being plugged.

Was the fuel pump strainer found to be plugged?

--

Go to Step 23

Go to Step 10

10
  1. Visually and physically inspect the seals and O-rings between the fuel pump, fuel filter, and the fuel pressure regulator for any of the following conditions:
    2. • Cracks
    • Splits
    • Deformed
    • Missing
  2. Repair as necessary.

Was a repair necessary?

--

Go to Step 25

Go to Step 11

11
  1. Check the fuel filter for a restriction.
  2. Replace the fuel filter if necessary. Refer to Fuel Pump and Fuel Filter Assembly Replacement

Was the fuel filter replaced?

--

Go to Step 25

Go to Step 22

12

  1. Turn ON the fuel pump with the scan tool.
  2. Wait for the fuel pressure to stabilize.
  3. Turn OFF the fuel pump.
  4. Monitor the fuel pressure on the fuel gauge.

Does the fuel pressure remain at or greater than the specified value for 5 minutes after the fuel pump is turned OFF?

147 kPa (21 psi)

Go to Step 13

Go to Step 17

13

Does the fuel pressure decrease during acceleration, cruise, or hard cornering?

--

Go to Step 14

Go to Diagnostic Aids

14

Visually and physically inspect the following items for restrictions:

    • Fuel filter
    • Fuel feed pipe

Was a restriction found?

--

Go to Step 15

Go to Step 16

15

Repair the restriction as necessary.

Is the action complete?

--

Go to Step 25

--

16
  1. Visually and physically inspect for any of the following conditions:
    2. • A restricted fuel pump strainer
    • An incorrectly positioned fuel pump pick-up
    • The incorrect fuel pump
    • A loose or missing fuel pump/tank baffle
  2. Repair as necessary.

Was a repair necessary?

--

Go to Step 25

Go to Step 24

17

  1. Turn ON the fuel pump with the scan tool.
  2. Pinch off the fuel pressure gauge adapter hose, fuel tank side (refer to callout 9 on the illustration), while monitoring the fuel gauge.
  3. Turn OFF the fuel pump.

Does the fuel pressure remain at or greater than the specified value for 5 minutes after the fuel pump is turned OFF?

147 kPa (21 psi)

Go to Step 19

Go to Step 18

18
  1. Check for a fuel leak in the following areas:
    2. • At the base of the fuel injectors
    • The fuel injectors
    • The fuel rail
  2. Repair as necessary.

Was a repair necessary?

--

Go to Step 25

Go to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F)

19
  1. Check the fuel feed pipe for leaks.
  2. Repair as necessary.

Was a repair necessary?

--

Go to Step 25

Go to Step 20

20

  1. Remove the fuel sender assembly. Refer to Fuel Sender Assembly Replacement .
  2. Visually and physically inspect the seals and O-rings between the fuel pump, fuel filter and the fuel pressure regulator for the following conditions.

    3. Inspect the entire fuel pump electrical circuit. Verify B+ at fuel pump connector and less than 5.0 ohms to ground.

    • Cracks
    • Splits
    • Deformed
    • Missing
  3. Repair as necessary.

Was a repair necessary?

--

Go to Step 25

Go to Step 21

21
  1. Check the fuel filter and the fuel pump for cracks or a leaking seam.
  2. Replace as necessary.

Was a component replacement necessary?

--

Go to Step 25

Go to Step 22

22
  1. Replace the fuel pressure regulator. Refer to Fuel Pressure Regulator Replacement .
  2. Attempt to start and run the engine.
  3. Monitor the fuel pressure gauge while the engine is running.

Is the fuel pressure within the specified value?

301-347 kPa

(44-50 psi)

Go to Step 25

Go to Step 24

23

  1. Replace the fuel pump strainer.
  2. Inspect the fuel system for the cause of the plugged fuel pump strainer.
  3. Repair as necessary.

Is the action complete?

--

Go to Step 25

--

24

Replace the fuel pump. Refer to Fuel Pump and Fuel Filter Assembly Replacement .

Is the action complete?

--

Go to Step 25

--

25
  1. Attempt to start and run the engine.
  2. Monitor the fuel pressure gauge while the engine is running.

Is the fuel pressure within the specified value?

301-347 kPa

(44-50 psi)

System OK

Go to Step 2