What is XCMG XE490D 3.3 CM2250 Fault Code 1691?

Fault Code 1691 indicates a Fuel Pump Actuator Circuit - Electrical Fault in the Cummins CM2250 engine used in XCMG XE490D excavators. This code is triggered when the Engine Control Module (ECM) detects an abnormal electrical signal from the fuel pump actuator circuit, including issues with voltage, resistance, or circuit continuity.

This fault is critical because the fuel pump actuator controls fuel pressure delivery to the common rail injection system. When this circuit malfunctions, the ECM cannot properly regulate fuel pressure, directly impacting engine performance, fuel efficiency, and potentially causing the engine to enter derate mode or fail to start. For used XCMG excavators with the CM2250 engine, this code often points to age-related electrical degradation rather than mechanical pump failure.

Common Symptoms

• Check Engine Light (CEL) illuminated on the instrument cluster with possible amber warning indicator
• Engine derate mode activated, limiting maximum RPM to 1500-1800 range and reducing hydraulic power
• Hard starting conditions or extended cranking time, especially during cold starts
• Rough idle or intermittent engine stumbling under load due to inconsistent fuel pressure
• Loss of power during digging or lifting operations, with noticeable reduction in cycle times

Potential Causes

The most common causes for Code 1691 on used XCMG XE490D excavators include:

• Damaged wiring harness between the ECM and fuel pump actuator, particularly at known rub points near the engine mount brackets and fuel filter housing
• Corroded or loose electrical connectors on the actuator itself or at the ECM harness connection (common in machines operating in wet or coastal environments)
• Failed fuel pump actuator solenoid due to internal coil breakdown or contamination from fuel system debris
• ECM internal driver circuit failure, though less common than harness issues in used equipment
• Chafed wires where the engine harness passes through bulkhead grommets or contacts sharp metal edges
• Poor ground connections at the engine block ground strap or ECM mounting points

How to Troubleshoot and Fix Code 1691

Step 1: Visual Inspection and Connector Check

Begin by visually inspecting the entire fuel pump actuator wiring harness from the ECM to the actuator. On used excavators, pay special attention to areas where the harness contacts the engine block, fuel lines, or mounting brackets. Check the actuator connector for corrosion, moisture intrusion, or bent pins. Clean connectors with electrical contact cleaner and apply dielectric grease before reconnecting.

Step 2: Electrical Testing with Multimeter

Disconnect the fuel pump actuator connector. Using a digital multimeter (DMM), measure resistance across the actuator terminals—typical specifications should be 2-6 ohms (consult Cummins service manual for exact values). Next, perform a voltage test at the harness connector with the ignition on: you should see battery voltage (approximately 12-14 volts) on the supply wire. Check for continuity between the ECM connector pins and the actuator harness connector to identify any open circuits.

Step 3: Advanced Diagnostics and Component Replacement

Connect Cummins INSITE diagnostic software or compatible scan tool to read live data and perform an actuator function test. Monitor commanded versus actual fuel pressure values. If electrical tests pass but the code persists, the actuator solenoid itself may have internal failure and requires replacement. Before replacing the actuator, inspect the ECM connector pins for corrosion or damage. On used machines, always replace the actuator connector pigtail if any corrosion is present, as this prevents recurring faults.

Disclaimer: This guide provides general troubleshooting information. Always consult the official XCMG and Cummins service manuals for exact specifications. For complex electrical diagnostics or ECM-related issues, seek assistance from a certified Cummins technician or authorized XCMG service center.