Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1989 Isuzu I-Mark LSFACTORY OEM SERVICE PROCEDURE
Fuel-Cut (Slow-Cut) System
- Check for trouble codes 22 and 42 before beginning this test. See the TESTS W/CODES - CARBURETED article. Ensure engine is at operating temperature. Connect tachometer.
- Run engine at 3500 RPM. Release accelerator. Measure voltage between Black/Green wire harness terminals of solenoid. Fuel-cut solenoid is located on carburetor, near choke heater. See Fig 1 .
- If voltage is less than 6 volts, go to step 4). If voltage is more than 6 volts, check for open between fuel-cut solenoid and ECM. If not open, adjust idle switch. If idle switch is okay, problem is with ECM or connector.
- Momentarily return throttle to idle and check voltage. If voltage does not change, go to step 5). If voltage rises to more than 6 volts and falls to low level at 2000-2500 RPM, check fuel-cut circuit and idle switch adjustment.
- If code 22 or 42 are not stored in ECM, the problem is poorly adjusted idle switch or (A/C) fast idle control diaphragm.
Factory Service Tools
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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.