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HOMESERVICE MANUALSISUZU1990AMIGO S, 2.3 L, MSG5EREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS - SYSTEM/COMPONENT TESTS - CARBURETEDFUEL SYSTEMFUEL CONTROLSYSTEM PERFORMANCE CHECK
1990 Isuzu Amigo S, 2.3 L, MSG5E

System Performance Check

1990 Isuzu Amigo S, 2.3 L, MSG5ESECTION System Performance Check
  1. Set parking brake with transmission in Neutral and block wheels. Disconnect purge hose from canister and plug. Connect tachometer and start engine. Disconnect carburetor mixture control (duty) solenoid. Ground mixture control solenoid dwell terminal. See Fig 1 .
  2. Run engine at 3000 RPM. Hold throttle at a constant opening and reconnect duty solenoid. Note RPM reading. Remove ground from duty solenoid dwell terminal before returning to idle. If RPM decreases more than 100 RPM, go to next step. If RPM decreases less than 100 RPM or increases, check duty solenoid connections. If connections are okay, repair internal carburetor problem.
  3. If RPM decreased more than 100 RPM, connect dwell meter (4-cyl. scale) to duty solenoid dwell terminal. See Fig 1 . Run engine at part throttle until upper radiator hose is warm. Return engine to idle and note dwell reading.
    NOTE: O2 sensor may cool off at idle, causing dwell to change from varying to fixed. If this happens, run engine at fast idle to warm sensor.
  4. If dwell is varying, go to next step. If dwell is fixed under 10 degrees, go to TEST 1. If dwell is fixed between 10-80 degrees, go to TEST 2. If dwell is fixed over 80 degrees, go to TEST 3.
  5. If dwell varied in step 4), check dwell again at 3000 RPM. If dwell is varying between 10-80 degrees, go to next step. If dwell is not varying between 10-80 degrees, repair internal carburetor problem.
  6. If dwell is between 10-80 degrees at 3000 RPM, check duty solenoid connector terminals. If connector terminals are okay, check Air Injector Reactor (AIR) management system. See AIR INJECTION REACTOR (AIR) MANAGEMENT SYSTEM under AIR INJECTION  under EMISSION SYSTEMS & SUB-SYSTEMS. If AIR management valve checks okay, clear codes if present. Refer to the TESTS W/CODES - 2.3L CARBURETED article in this section.
Fig 1: Locating Mixture Control Solenoid Dwell Terminal
G90B20207Courtesy of ISUZU MOTOR CO.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.