Abstract: Oil pressure delay check valve and pressure switch for unattended Diesel engine to shut off the fuel supply valve after a low oil pressure signal, and to delay opening of the valve for a predetermined time interval. This delay is attained by the closing of a normally open pressure switch upon pressures decreasing from the order of 8 psi and by bleeding the oil pressure past a check valve through a bleeder tube in cooperation with an accumulator, from a pressure in the order of 8 psi to a pressure in the order of 5 psi to accommodate the opening of a normally closed switch as the pressure decrease from the order of 5 psi. The two switches are in series and when closed, energize the solenoid of an electrically energizable valve to shut off the supply of fuel to the Diesel engine. As the oil pressure decreases, one pressure switch will close and remain closed while the other pressure switch will open in a predetermined time delay interval and effect opening of the fuel supply valve.