CM850 Electronic Control System – FAULT CODE 2215 (ISB/QSB Automotive, Industrial, or Marine Application)

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Overview

Fuel System SMALL | MEDIUM | LARGE

Circuit Description

The fuel pressure control loop relies on fuel pressure supplied to the high-pressure pump by the electric lift pump and low-pressure gear pump. The ECM monitors rail fuel pressure and engine operating conditions and changes the flow command to maintain the proper rail fuel pressure. Changes to the flow command result in opening (or closing) of the fuel pump actuator to supply more (or less) fuel to the high-pressure pump.

The fuel flow circuit includes, in the following order of fuel flow:

• Fuel tank
• OEM fuel supply line
• OEM filter
• ECM cooling plate
• Electric lift pump
• Fuel filter
• Gear pump
• Fuel pump actuator
• High-pressure fuel pump
• Rail fuel (includes fuel pressure relief valve and pressure sensor)
• High-pressure fuel lines
• High-pressure fuel connectors
• Injectors
• Return to tank.

Component Location

The fuel pump is located at the rear of the engine, on the intake side of the engine. Refer to Procedure 100-002 in Section E for a detailed component location view.

Shop Talk

General Information:

Fault Code 2215 logs when measured rail fuel pressure remains at least 10 MPa [1450 psi] less than commanded rail fuel pressure. Once detected, Fault Code 2215 will remain active until the engine is turned off or until the measured rail fuel pressure matches the commanded rail fuel pressure. When a condition exists that causes Fault Code 2215 to become active, it is typical for the fault code to become active when the engine is heavily loaded and become inactive when the engine is lightly loaded.

Fault Code 2292 sets when the ECM commands the fuel pump actuator to open more than expected to maintain rail pressure.

When Fault Code 2215 occurs, the fuel system has lost its ability to maintain rail fuel pressure. Causes of this fault can include:

• Fuel inlet restrictions
• Fuel filter plugging
• Excessive air in the fuel
• Loss of prime during cranking
• Low fuel lift pump pressure (automotive/marine engines)
• Stuck or restricted electronic fuel control actuator
• System return (excessive return flow from the injectors, high-pressure pump, or rail pressure relief valve)
• Tampering.

If the drain line is restricted completely, the high pressure fuel pump will fail, causing internal leakage. Prior to a pump malfunction, fault codes indicative of drain line restriction will occur. The fault codes are Fault Code 2216, 2293, or 449. Following the malfunction, these fault codes will go inactive and Fault Code 2215, which is indicative of leakage, will be active. If troubleshooting Fault Code 2215 results in replacement of the pump and there are inactive counts of Fault Codes 2216, 2293, or 449, the drain line must be inspected and measured for restriction to prevent repeat high pressure pump malfunctions.

Inactive Fault Code:

Troubleshooting inactive Fault Code 2215 can be very difficult. The fault code must be active for any of the outlined procedures in which the engine is operated during the test. For engines with high counts of inactive Fault Code 2215, operate the engine on a chassis dynamometer or a diagnostic road test to duplicate the fault code. The most common causes of intermittent Fault Code 2215 that are difficult to recreate are leaking high pressure connectors that only leak when the engine is hot and the fuel is hot, and intermittent fuel supply restriction, such as debris floating in the fuel tank.

If Fault Code 2215 is inactive and there are no existing performance complaints, it is possible the engine ran out of fuel or the fault became active if the engine was not primed following a fuel filter replacement. Clear the inactive fault codes.

Engine No Start:

If the engine will not start and Fault Code 2215 becomes active during cranking, but no speed sensor fault codes exist, monitor rail fuel pressure with INSITE™ electronic service tool. If the rail fuel pressure is low, check the following:

• Fuel system prime (make sure there is fuel in the tanks and the system is primed)
• Fuel lift pump pressure. See the ISBe and ISB Common Rail Fuel System Series Engines Service Manual, Bulletin 4021271.Refer to Procedure 005-045 in Section 5
• Injector and pressure relief valve leakage
• Fuel pump discharge test.

Lift Pump:

When measuring the voltage at the electric lift pump, the lift pump must be connected to the engine harness during the test. The positive and negative probes of the digital volt ohm multimeter must be connected to the circuit. This connection can be made with a 2-pin Deutsch™ breakout cable, Part Number 3163531.

24 volt applications that use a 24 volt Lift Pump Wiring Harness:

Some 24 volt applications use an additional component in the lift pump circuit. The 24 volt lift pump wiring harness consists of a relay and voltage regulator. Power supplied by the ECM engages the relay. An OEM-supplied +24-VDC power source is then delivered to the voltage regulator through the relay. The voltage regulator reduces the +24-VDC to +12-VDC, which is then supplied to the lift pump.

The regulator is load-dependant. In order for the regulator to reduce the +24-VDC to +12-VDC, the lift pump must be plugged in and running in diesel fuel. Also, the multimeter test leads must be connected to the lift pump SUPPLY and RETURN wires. This can be achieved with a breakout harness. If the voltage is measured with the lift pump disconnected, the meter will display system voltage (+24-VDC). If the multimeter ground test lead is placed on the cylinder block or anywhere else other than the lift pump RETURN wire, the display will read system voltage (+24-VDC).

With the lift pump plugged in and running in diesel fuel, the voltage measurement should not exceed +14-VDC. If the voltage is greater than +14-VDC, the regulator is damaged.

Refer to Troubleshooting Fault Code t05-2215