Electrical shut-off solenoid (ESOS)
The ESOS is fitted to the right-hand side of the cylinder block, at the rear of the fuel injection pump. When the solenoid is de-energized, a control rod pushes the fuel control rack to the ‘no fuel position’ in the injection pump. The unit operates from a 12V or 24V supply depending on the option in an ‘energize to run’ condition, an electrical failure will give automatic fuel shut-off.
 
U85206452 is a Fuel Shut Off Solenoid For Caterpillar Cat 3024 Perkins HL403C-15 HR404C-22T 402D 403D 404D 404C 403C engines.