Case IH 268 – Engine Controller (ENG): Fuel Pressure in pump is not changing with operating conditions.

The engine control unit is commanding a change in fuel pressure based on engine speed and load, but the actual pressure inside the injection pump is not responding. This code is heavily associated with the Cummins Accumulator Pump System (CAPS) failing to maintain or adjust pressure, often resulting in intermittent power loss, engine bouncing, or a complete failure to prime.

• MX Magnum
• STX Steiger
• MX180
• MX200
• MX220
• MX240
• MX255
• MX270
• MX285
• Magnum series
• STX275
• STX325
• Axial-Flow 2388
• Axial-Flow 2577
• Axial-Flow 2588
• SPX4410
• TG210
• TG230
• TG255
• TG285
• TJ275
• TJ325

1. 1

   Check for Fuel Starvation: Inspect all inline fuel filters and water separators for clogs or heavy contamination.

2. 2

   Check for Air Leaks: Inspect the suction side of the injection pump and fuel lines for air leaks. Tighten fuel lines and check for defective fuel filter case gaskets.

3. 3

   Verify Lift Pump Operation: Ensure the electric fuel lift pump is operating and priming the system (a failed lift pump will often throw a related code, ENG 278).

4. 4

   Check CAPS Control Valves: Ensure there are no accompanying electrical fault codes for these valves (e.g., ENG 271, 272, 273, 274) which would indicate a wiring short or open circuit rather than a mechanical pump failure.

1. 1

   Replace Fuel Filters

   Remove and replace the primary and secondary spin-on fuel filters.

2. 2

   Bleed the System

   Prime the fuel system to ensure all air is purged from the lines.

3. 3

   Test Operation

   Run the machine under load to see if the fuel pressure normalizes and the code clears.

4. 4

   Replace or Convert the CAPS Pump

   If the tractor still loses power, fails to prime, or the code persists, the CAPS injection pump has suffered an internal mechanical failure. You must remove the defective CAPS pump and install a replacement. Note: Because CAPS pumps are prone to failure, many mechanics and dealers recommend installing a Heavy Duty In-Line "P-Pump" (7100) conversion kit rather than installing another factory CAPS pump.