Chapter 5: Fuel System
Covers the MPI (multi-point fuel injection) fuel system for both SOHC (XR, naturally aspirated) and DOHC (VR, intercooled turbo — our truck’s 4A30 DOHC turbo, 3A/T, 4WD) engines: system component charts, specifications, MUT diagnostics and ECU/DTC codes, ECU and harness pin guides, sensor location guide, idle/TPS adjustment, fuel pressure testing, injectors, throttle body, emission controls, catalytic converter, fuel tank system, and accelerator cable.
Extra-care sections: 46-48 (ECU diagnostics, DTC codes, and pin guides) contain the chapter’s worst OCR damage — several tables could only be partially reconstructed and carry heavy row-by-row flags. Cross-page spec discrepancies (fuel pressure, idle RPM) are flagged where found; see each file for detail.
- MPI Fuel System & Component Chart — SOHC — sensor/ECU loop and fuel/vacuum circuit for the naturally-aspirated SOHC (XR) engine, M/T and A/T variants.
- MPI Fuel System & Component Chart — DOHC — sensor/ECU loop and turbo-specific circuit (waste gate, boost, knock sensor) for the DOHC (VR) engine.
- Data & Specifications — timing, idle rpm, TPS/intake/water temp sensor resistance, fuel pressure, injector coil resistance.
- Tools — MPI analyzer, test harnesses, injector test set/adapters, hose adapters, test leads.
- MUT Hand Held Diagnostics & ECU Troubleshooting Codes — warning lamp flash-code procedure, common failure codes, complete DTC code list.
- Engine ECU Connector Pin Guide — DOHC (52-pin) / SOHC (46-pin) connector voltage specs by circuit — heavily flagged, pin-number/circuit row alignment not fully recoverable from OCR.
- Diagnostic Harness Pin Guide — harness-side ohm test table for the same connectors, better-preserved than sec. 47 but still flagged in places.
- MPI Fuel System Sensor & Component Location Guide — underhood component location legend; only one letter-callout pairing (Intake Air Temp Sensor = “D”) is confirmed.
- TPS & SAS Idle Speed System — SAS gap/idle adjustment and TPS voltage check, DOHC Turbo and SOHC procedures.
- Fuel Line Pressure Test — fuel pressure gauge setup and line pressure test procedure; cross-page pressure-figure discrepancy flagged.
- Fuel Injector System — injector ticking/ohm test, individual injector bench test rig, fuel rail component removal.
- Throttle Body Removal — throttle body removal/installation procedure.
- Emission Control Schematics — SOHC & DOHC — emission system and vacuum hose routing diagrams for both engines.
- Catalytic Converter — component list, torque specs, exhaust over-heat sensor ohm test.
- Fuel Pump-Filter-Tank System — fuel tank removal prep and component removal, filler hose alignment note.
- Accelerator Cable System — accelerator cable and pedal removal.