Cat c12 trim code locations

It varies with different arrangements. You have the engine serial number handy or able to get it?

 

Yes, you have the integral pressure regulator that is located behind fuel return fitting. Port 22 is where you would check fuel pressure.

 

Have you disconnected fuel suction hoses and make sure they are not obstructed? Needs free return hose also. Try running it from a bucket bypassing hoses and primary fuel filter.

 

Did you check the check valves in the hand primer pump also?

 

Here is description of fuel supply system:
The low pressure fuel system supplies fuel from the fuel tank to the injectors. The low pressure fuel system has three basic functions:

• • The low pressure fuel system supplies fuel to the injectors for combustion.
    
  • The low pressure fuel system supplies fuel to the injectors for cooling.
    
  • The low pressure fuel system supplies fuel to the fuel system in order to remove air.

The major parts in a low pressure fuel system consist of the following components:

• • Fuel tank
    
  • Fuel transfer lines
    
  • Primary fuel filter or water separator
    
  • Fuel transfer pump
    
  • Secondary fuel filter
    
  • Fuel priming pump
    
  • Fuel pressure regulator valve

The electronic unit injectors, the fuel transfer pump, the engine control module, sensors, and actuators are part of the low pressure fuel system.
In the low pressure fuel system, the fuel is pulled from the fuel tank to the primary fuel filter or to the water separator. The primary fuel filter removes large debris from the fuel before the fuel flows into the transfer pump. The fuel transfer pump is a gear pump that contains a pressure relief valve. Fuel flows from the outlet port of the transfer pump to the secondary fuel filter. All 1999 and newer engines use a 2 micron fuel filter. The 2 micron filter removes small abrasive contaminants from the fuel system, which can cause damage to the unit injectors.
The fuel filter base contains a hand operated fuel priming pump. The fuel priming pump removes air from the system when a fuel filter has been changed or a unit injector has been changed. The priming pump pulls fuel from the tank, around the transfer pump and into the filter. The transfer pump pushes fuel through the supply passage in the cylinder head and back to the tank.
The fuel pressure regulator consists of a check valve that is spring loaded. The pressure relief valve opens at approximately 60 to 125 PSI. When the engine is in the off position and the fuel pressure drops below 60 PSI, the check valve closes. The check valve closes in order to prevent the fuel in the cylinder head from draining back into the fuel tank. Retaining the fuel in the head maintains a supply of fuel for the injectors during start-up requirement.
The engine control module controls major engine functions. Sensors are electronic devices that monitor engine performance parameters. The pressure sensor, the temperature sensor and the speed sensor provide information to the electronic control module by a signal voltage. Actuators are electronic devices which use electrical currents from the engine control module to change engine performance. An example of an actuator is an injector solenoid.

The primer should get very stiff, but will "soften" after cranking. I am really curious what fuel pressure is when cranking. Need 30-40 PSI to fire.