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Test S - Fuel Control

NOTE: See CIRCUIT TESTS  before performing this test. Fuel contaminated engine oil may affect service codes 41 and 42. If this is suspected, remove PCV valve from valve cover and repeat QUICK TEST  . If problem is corrected, change engine oil and filter.
  1. Turn key off and wait 10 seconds. Install fuel pressure gauge. Start and run engine. Fuel pressure must be 35-45 psi (2.46 3.16 kg/cm2 ). Fuel pressure must remain at 35-45 psi (2.5-3.2 kg/cm2 ) for 60 seconds after key is turned off. If engine will not start, cycle the key from off to on a few times to build up fuel pressure. If fuel pressure is outside range, check electric fuel pump and fuel pressure regulator. If fuel pump does not hold pressure for 60 seconds, go to step 6). If fuel pressure is correct, go to next step.
  2. With pressure gauge installed, cycle key from off to on a few times to pressurize system. Locate and disconnect fuel pump relay. Crank engine for 5 seconds and take pressure reading immediately after cranking. If pressure reading is 10-20 psi (0.7-1.4 kg/cm2 ), the EEC system is NOT at fault for no start. If problem is rough running, missing, fuel code or incorrect pressure, go to next step.
    NOTE: Make sure that fuel is of good quality and not contaminated by air or water, as pressure readings may be incorrect with bad or contaminated fuel. Also, pressure drop will be greater when engine is cold than when engine is warm. If coolant is 200°F (93°C) pressure should drop approximately 10 psi (0.7 kg/cm2 ) in 5 seconds while a pressure drop of 20 psi (1.4 kg/cm2 ) should occur in 5 seconds with engine coolant at 60°F (15.6°C).
  3. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin 37 and 58 for injector bank 1. Measure resistance between test pin 37 and 59 for injector bank 2. If both readings are between 5.0 and 6.5 ohms, go to step 5). If readings are not between 5.0 and 6.5 ohms, go to next step.
  4. With key off, breakout box installed and ECA disconnected, set DVOM on 200-ohm scale. Disconnect all injectors on suspect bank. Measure resistance of each injector by connecting 1 injector at a time, and reading resistance between test pin 37 and 58 for bank 1 or test pin 37 and 59 for bank 2. If all readings are not between 16.0 and 18.0 ohms, repair harness and/or connectors on suspect bank for short or open. If okay, replace faulty injector(s). Repeat QUICK TEST  . If all readings are between 16.0 and 18.0 ohms, go to next step.
  5. With key off and breakout box installed, connect ECA to box. Connect a non-powered 12-volt test lamp between test pin 37 and 58. Crank or start engine. Repeat test between test pin 37 and 59. If lamp does not light on one or both tests, check for 12 volts at test pin 37 and 57. If okay, replace ECA. Repeat QUICK TEST  . If lamp is bright on one or both tests, check suspect bank for shorts to ground. If okay, replace ECA. Repeat QUICK TEST  . If lamp glows dimly on both tests, go to next step.
  6. Connect tachometer to engine and run engine at idle. Disconnect and reconnect injectors 1 at a time. Check RPM drop for each injector. Each injector should produce at least a 100 RPM momentary drop (ISC will attempt to correct RPM). If drop does not take place, replace faulty injector. Repeat QUICK TEST  . If drop takes place, fuel delivery is okay. Problem is common to all cylinders such as vacuum or air leaks, fuel contamination, faulty EGR, etc.
  7. Code 42 Displayed. This code indicates an always rich condition. Turn key off and wait 10 seconds. Disconnect harness at HEGO sensor. Install a jumper wire between HEGO circuit at connector and ground at engine block. Perform KEY ON/ENGINE RUNNING SELF-TEST  . If service code 41 is displayed, go to step 9). If code 41 is not displayed, go to next step.
  8. Turn key off and wait 10 seconds. Install breakout box and set DVOM on 200-ohm scale. Measure resistance between test pin 49 and HEGO ground at engine block. Measure resistance between test pin 29 and HEGO circuit at connector. If both circuits are less than 5 ohms, disconnect ECA connector. Inspect connector for corrosion or damage. If okay, replace ECA and repeat QUICK TEST  . If both circuits are not less than 5 ohms, repair circuit having a resistance higher than 5 ohms. Repeat QUICK TEST  .
  9. Set DVOM on 20-volt scale. Disconnect HEGO sensor from harness. Connect DVOM from HEGO sensor to engine ground. Disconnect PCV hose. Start engine and run at 2000 RPM. If reading is less than 0.4 volts within 1 minute, HEGO sensor is okay. Go to step 1). If reading is not less than 0.4 volts within 1 minute, replace HEGO sensor. Repeat QUICK TEST  .
  10. Code 41 Displayed. This code indicates an always lean condition. Run engine at 2000 RPM for 2 minutes. Turn key off and wait 10 seconds. Perform KEY ON/ENGINE RUNNING SELF-TEST  . If code 41 is not displayed, go to step 15) If code 41 is displayed, go to next step.
  11. Turn key off and set DVOM on 20-volt scale. Disconnect HEGO sensor from harness. Connect DVOM to HEGO sensor and engine ground. Disconnect Air Charge Temperature (ACT) sensor. Start and run engine at 2000 RPM. If DVOM reading is not more than 0.5 volts within 1 minute, replace HEGO sensor. Repeat QUICK TEST  . If DVOM reading is more than 0.5 volts within 1 minute, go to next step.
  12. Turn key off. Install breakout box, leaving ECA disconnected. Measure resistance between test pin 49 and engine block ground. Measure resistance between HEGO circuit at connector and test pin 29. If both readings are not less than 5 ohms, repair circuit having a resistance greater than 5 ohms. Repeat QUICK TEST  . If both readings are less than 5 ohms, go to next step.
  13. With key off, breakout box installed and ECA disconnected, set DVOM on 200,000-ohm scale. Measure resistance between test pin 29 and 40. If reading is less than 10,000 ohms, repair cause of resistance to ground. If reading is 10,000 ohms or more, go to next step.
  14. Turn Key off and connect HEGO sensor. Ensure that ACT sensor is disconnected. Start and run engine at 2000 RPM for 1 minute, then allow engine to return to idle. Perform KEY ON/ENGINE RUNNING SELF-TEST  . Check for code 41. Ignore all other codes at this time. If code 41 is displayed, disconnect ECA connector and inspect for damage. If connector is okay, replace ECA and repeat QUICK TEST  . If code 41 is not displayed, connect ACT sensor. HEGO sensor input circuit is okay, go to step 1).
  15. Turn key and engine off. Set DVOM on 200-ohm scale. Measure resistance (at room temperature) between RUN circuit and ground at HEGO connector. If reading is less than 2.5 ohms or more than 5.0 ohms, replace HEGO sensor. If reading is between 2.5 and 5.0 ohms, go to next step.
  16. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Connect DVOM positive lead to RUN circuit and negative test lead to ground at HEGO harness connector. If reading is 10.5 volts or higher, HEGO sensor circuit is okay. Check non-EEC related items. If reading is less than 10.5 volts, go to next step.
  17. Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Measure resistance of ground circuit from HEGO harness connector to battery ground. If reading is less than 5 ohms, repair open in RUN circuit. If reading is 5 ohms or more, repair open in ground circuit.
Fig 1: 2.9L EFI Fuel Control Circuits
G11092
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