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Test R - Fuel Control

NOTE: See HOW TO USE CIRCUIT TESTS  before performing this test.
  1. Code 41 Displayed. If engine ran for more than 2 minutes before performing ENGINE RUNNING SELF-TEST, go to next step. If engine did not run for more than 2 minutes, prepare vehicle and repeat ENGINE RUNNING SELF-TEST.
  2. Turn key off. Connect ECA and EGO sensor. Disconnect thermactor air supply hose at air pump and cap hose. Perform ENGINE RUNNING SELF-TEST. If code 11 or 42 is present, treat as code 44. Return to ENGINE RUNNING SELF-TEST and service code(s) as necessary. If code 41 is present, leave thermactor hose disconnected and go to next step. If code 44 is present, return ENGINE RUNNING SELF-TEST and service code as necessary.
  3. Turn key off and wait 10 seconds. With thermactor hose disconnected, disconnect harness at Feedback Control (FBC) solenoid. Perform ENGINE RUNNING SELF-TEST. Check for code 41. Ignore all other codes at this time. If code 41 is not displayed, go to step 5). If code 41 is displayed, go to next step.
  4. Turn key off and wait 10 seconds. With FBC solenoid and thermactor hose disconnected, start and run engine at part throttle for 2 minutes. Turn key off and wait 10 seconds. Perform ENGINE RUNNING SELF-TEST while holding choke 3/4 closed. DO NOT  stall engine. If code 41 is displayed, connect all components and go to step 6). If code 41 is not displayed, replace FBC solenoid and repeat QUICK TEST  . If code 41 is still present, service carburetor.
  5. Turn key off and wait 10 seconds. Connect thermactor air hose. Leave FBC solenoid disconnected. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. With DVOM on 200,000-ohm scale, measure resistance from test pin 58 to pins 20, 40 and 46. If any reading is less than 10,000 ohms, repair short circuit and repeat QUICK TEST  . If all readings are 10,000 ohms or more, replace ECA. Connect all components and repeat QUICK TEST  .
  6. Turn key off. With EGO sensor disconnected, start and run engine for 2 minutes. Set DVOM on 20-volt scale. With engine running, hold choke 3/4 closed. DO NOT  stall engine. Measure voltage between EGO sensor pigtail and battery negative terminal. If reading is less than 0.45-volts, replace EGO sensor and repeat QUICK TEST  . If reading is 0.45-volts or more, go to next step.
  7. Turn key off and wait 10 seconds. Disconnect EGO sensor. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. With DVOM on 200-ohm scale, measure resistance between test pin 29 and EGO sensor circuit at EGO sensor connector. Measure resistance between test pin 49 and pins 40 and 60. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, connect ECA and EGO sensor, then repeat QUICK TEST  . If all readings are less than 5 ohms, go to next step.
  8. Turn key off and wait 10 seconds. With thermactor and FBC solenoid connected, disconnect harness at EGO sensor. With DVOM on 200,000-ohm scale, measure resistance between negative battery terminal and EGO sensor circuit at EGO sensor connector. If reading is less than 10,000 ohms, repair short circuit. Remove breakout box, connect ECA and EGO sensor, then repeat QUICK TEST  . If reading is 10,000 ohms or more, replace ECA. Connect ECA and EGO, then repeat QUICK TEST  .
  9. Codes 42 & 47 Displayed. If choke assembly binds or sticks, service choke assembly and repeat QUICK TEST  . If choke functions properly without sticking or binding, go to next step.
  10. Start and run engine at part throttle for 2 minutes. Turn key off and wait 10 seconds. Disconnect harness at EGO sensor. Install a jumper wire and connect harness EGO circuit to ground. Perform ENGINE RUNNING SELF-TEST. Check for code 41. Ignore all other codes at this time. If code 41 is displayed, go to next step. If code 41 is not displayed, go to step 16).
  11. Turn key off and wait 10 seconds. Disconnect a 7/32" vacuum hose to create a vacuum leak. Set DVOM on 20-volt scale. Disconnect EGO sensor from harness and connect DVOM from EGO sensor to engine ground. Run engine at 2000 RPM for 2 minutes while observing DVOM. If reading is less than 0.4-volts, EGO sensor is okay. Go to next step. If reading is more than 0.4-volts, replace EGO sensor, connect vacuum hose, and repeat QUICK TEST  .
  12. Turn key off and wait 10 seconds. Connect 7/32" vacuum hose. Disconnect FBC solenoid and set DVOM on 200-ohm scale. Measure FBC solenoid resistance. If resistance is 15 to 30 ohms on 2150 carburetor or 30 to 60 ohms on YFA carburetor, connect FBC solenoid and go to next step. If resistance is incorrect, replace FBC solenoid and repeat QUICK TEST  .
  13. Turn key off and wait 10 seconds. Deactivate QUICK TEST  and disconnect harness at FBC solenoid. Set DVOM on 20-volt scale. Turn ignition on, leaving engine off. Measure voltage between negative battery terminal and VPWR at FBC solenoid connector. If reading is less than 10-volt`s, connect FBC solenoid, repair open circuit and repeat QUICK TEST  . If reading is 10-volts or more, go to next step.
  14. 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. With DVOM on 200,000-ohm scale, and FBC solenoid disconnected, measure resistance between test pin 58 and 37. If reading is less than 10,000 ohms, repair short circuit to power and repeat QUICK TEST  . If reading is 10,000 ohms or more, go to next step.
  15. Turn key off and wait 10 seconds. Leave FBC solenoid disconnected. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. With DVOM on 200-ohm scale, measure resistance between test pin 58 and FBC circuit at harness connector. If reading is less than 5 ohms, replace ECA. Remove breakout box, connect ECA and FBC solenoid, then repeat QUICK TEST  . If reading is 5 ohms or more, repair open circuit. Remove breakout box, connect ECA and FBC solenoid, then repeat QUICK TEST  .
  16. Turn key off and wait 10 seconds. Disconnect vacuum hose between canister purge solenoid and canister, and plug both ends. Repeat ENGINE RUNNING SELF-TEST. If code 42 is displayed, go to next step. If code 42 is not displayed, go to TEST Y - CANISTER PURGE (CANP) CHECK  , step 1).
  17. Turn key off and wait 10 seconds. Install breakout box. Measure resistance between test pin 49 and EGO sensor ground at engine block. Measure resistance between test pin 29 and EGO sensor harness connector. If both readings are less than 5 ohms, disconnect ECA and check connector for damage or corrosion. If there is no damage or corrosion, replace ECA and repeat QUICK TEST  . If resistance is higher than 5 ohms, repair circuit having a resistance greater than 5 ohms and repeat QUICK TEST  .
  18. Code 43 Displayed. Start and run engine at 2000 RPM for 2 minutes. Turn key off and wait 10 seconds. Perform ENGINE RUNNING SELF-TEST. If code 43 is not displayed, service other codes as necessary. If code 43 is displayed, go to next step.
  19. If there are any exhaust leaks at manifold or inlet pipe, repair as necessary and repeat QUICK TEST  . If there are no leaks present, go to next step.
  20. Start engine and allow to idle. If idle quality weakens and remains poor during and after QUICK TEST  , service carburetor. If idle quality is stable, replace EGO sensor and repeat QUICK TEST  .
Fig 1: FBC Fuel Control Circuits
G2559
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