When the Focus car cools down, the valve closes.

Hello, we need to check several points: 1 whether the signal of water temperature sensor is correct. 2 Whether the spark plug gap is too large and needs to be replaced. 3 cold car gasoline pressure is insufficient. Usually the gasoline pump leaks oil. 4 Clean the carbon deposit on the throttle and air intake. Excessive carbon deposition will cause fuel to enter the cylinder and become thinner. I hope my answer can help you, and I wish you a happy life! If there is something wrong with your car, ask the car mechanic. 4S shop professional technician, 10 minutes to solve.