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Test J - Fuel Control Test

  1. Code 41. If engine ran for more than 2 minutes before performing Key On-Engine Running Self-Test, go to next step. If engine did not run for more than 2 minutes, prepare vehicle and perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  .
  2. Before continuing test, check oxygen sensor connection and ground for good connections. Check intake and exhaust manifolds for leaks. If all okay, go to next step. If not okay, repair problem and repeat KEY ON-ENGINE RUNNING (KOER) SELF-TEST  .
  3. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Disconnect oxygen sensor harness. With DVOM on 200,000 ohm scale, measure resistance from oxygen sensor signal circuit of oxygen sensor harness connector to vehicle battery negative terminal. If less than 10,000 ohms, repair short circuit and repeat QUICK TEST  . If 10,000 ohms or more, go to next step.
  4. Turn ignition off. Reconnect ECA and oxygen sensor. Disconnect thermactor and cap air supply hose at air pump. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . Because thermactor hose is disconnected, code 11 does not indicate a pass. Treat code 11 as a code 44. If code 41 is present, leave thermactor hose disconnected and go to next step. If code 44 is present, perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . Ignore all other codes at this time.
  5. Turn ignition off and wait 10 seconds. With thermactor hose disconnected, disconnect harness at FCS. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . If no code 41, go to step  7 . If code 41, go to next step. Ignore all other codes at this time.
  6. Turn ignition off and wait 10 seconds. With FCS and thermactor hose disconnected, start and run engine at part throttle for 2 minutes. Turn ignition off and wait 10 seconds. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  while holding choke 3/4 closed. DO NOT  stall engine. If code 41, reconnect all disconnected components and go to step  10 . If no code 41, replace FCS and repeat KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . If code 41 still present, service carburetor.
  7. Turn ignition off and wait 10 seconds. Reconnect thermactor hose and FCS. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and leave ECA disconnected. With DVOM on 200,000 ohm scale, measure resistance from box pin 58 to pins 20, 40 and 46 in turn. If any less than 10,000 ohms, repair short circuit and repeat QUICK TEST  . If all readings 10,000 ohms or more, go to next step.
  8. Turn ignition off. With breakout box installed, connect ECA to breakout box. Start and run vehicle at part throttle for 2 minutes. Turn ignition off and wait 10 seconds. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  while holding choke 3/4 closed. DO NOT  stall engine. If no code 41, go to next step. If code 41, replace FCS. Remove breakout box, reconnect FCS and ECA and repeat QUICK TEST  .
  9. Turn ignition off and wait 10 seconds. With breakout box installed and ECA connected, disconnect harness at FCS. With DVOM on 2,000 ohm scale, measure resistance from feedback circuit of FCS harness connector to battery negative terminal. Then measure from vehicle power circuit of FCS harness connector to battery negative terminal. If either reading is less than 1,000 ohms, replace FCS and repeat QUICK TEST  . If both readings are 1,000 ohms or more, remove breakout box, replace ECA, and repeat QUICK TEST  .
  10. Turn ignition off and wait 10 seconds. With thermactor and FCS connected, disconnect harness at oxygen sensor. With DVOM on 200,000 ohm scale, measure resistance from oxygen sensor circuit of oxygen sensor harness connector to battery negative terminal. If less than 10,000 ohms, replace ECA and repeat QUICK TEST  . If 10,000 ohms or more, go to next step.
  11. Turn ignition off. With oxygen sensor disconnected, start and run engine for 2 minutes. Place DVOM on 20 volt scale. With engine running, hold choke 3/4 closed and measure voltage from oxygen sensor pigtail terminal to battery negative terminal. DO NOT  stall engine. If less than .45 volt, replace oxygen sensor and repeat QUICK TEST  . If .45 volt or more, go to next step.
  12. Ignition on and oxygen sensor disconnected. With DVOM on 20 volt scale, measure voltage from oxygen sensor circuit of oxygen sensor harness connector to battery negative terminal. If less than 2 volts, go to next step. If 2 volts or more, repair short circuit and repeat QUICK TEST  .
  13. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and leave ECA disconnected. Disconnect oxygen sensor. With DVOM on 200 ohm scale, measure resistance from oxygen sensor circuit of oxygen sensor harness connector to box pin 29. Then measure from box pin 49 to pins 40 and 60. If all readings less than 5 ohms, replace ECA and repeat QUICK TEST  . If any 5 ohms or more, repair open circuit and repeat QUICK TEST  .
  14. Code 42 and/or 47. If choke functions properly without sticking or binding, go to next step. If not, service choke assembly and repeat QUICK TEST  .
  15. Start and run engine at part throttle for 2 minutes. Turn ignition off and wait 10 seconds. Disconnect harness at oxygen sensor and jumper oxygen sensor circuit of oxygen sensor harness connector to ground. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . If code 41, go to next step. If no code 41, go to step  22 . Ignore all other codes.
  16. Turn ignition off and wait 10 seconds. Reconnect oxygen sensor. Disconnect 7/32" vacuum line at intake manifold vacuum tree. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . If engine stalls, repeat test while manually maintaining engine speed at about 1500 RPM. If code 42 and/or 47 still present, replace oxygen sensor and repeat QUICK TEST  . If code 42 and/or 47 not present, go to next step. Ignore all other codes.
  17. Turn ignition off and wait 10 seconds. Reconnect vacuum hose at intake manifold vacuum tree. Disconnect FCS and place DVOM on 200 ohm scale. Measure resistance between terminals on FCS. If resistance is 15-30 ohms, reconnect FCS and go to next step. If not 15-30 ohms, replace FCS and repeat QUICK TEST  .
  18. Turn ignition off and wait 10 seconds. Enter Output State Check. Place DVOM on 20 volt scale. Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  until end of Continuous code display. DVOM will indicate 0 volts. Depress and release throttle. If DVOM indicated high voltage, remain in Output State Check and go to next step. If DVOM did not indicate high voltage, depress throttle to wide open position and release. If voltage still does not go high, go to TEST D  , step 13
  19. While in Output State Check, turn ignition on and place DVOM on 20 volt scale. Connect DVOM between feedback circuit of FCS connector and battery negative terminal. While observing DVOM, depress and release throttle several times to cycle output on and off. If FCS cycles on and off, go to TEST L  . If FCS does not cycle on and off, exit Output State Check and go to next step.
  20. Turn ignition off and wait 10 seconds. Deactivate QUICK TEST and disconnect harness at FCS. With DVOM on 20 volt scale, turn ignition on. Measure voltage from voltage power circuit of FCS harness connector to battery negative terminal. If less than 10 volts, reconnect FCS, repair open circuit and repeat QUICK TEST  . If 10 volts or more, go to next step.
  21. Turn ignition off and wait 10 seconds. Disconnect harness at FCS. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and leave ECA disconnected. With DVOM on 200 ohm scale, measure resistance from feedback circuit of FCS harness to box pin 58. If less than 5 ohms, replace ECA and repeat QUICK TEST  . If 5 ohms or more, repair open circuit and repeat QUICK TEST  .
  22. Turn ignition off and wait 10 seconds. Reconnect oxygen sensor. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and leave ECA disconnected. Turn ignition on. With DVOM on 20 volt scale, measure voltage from box pin 29 to battery negative terminal. If less than .4 volt, replace ECA and repeat QUICK TEST  . If code 42 still present, go to TEST L  . If .4 volt or more, repair short circuit and repeat QUICK TEST  . 23 Code 43. Start and run engine at 2000 RPM for 2 minutes. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . If code 43, go to next step. If no code 43, service other codes as necessary.
  23. If there are any leaks at intake manifold or inlet pipe, repair as required and repeat QUICK TEST  . If okay, go to next step.
  24. Start engine and allow to idle. If idle quality weakens and remains poor during and after Quick Test, service carburetor. If not, replace oxygen sensor and repeat QUICK TEST  .
Fig 1: Fuel Control Circuit
G9344
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