Chrysler Chrysler High Fuel Pressure High Fuel Pressure - 86 Chrysler 2.5L T.B.I. Runs rich and sets Code 52 1. Check fuel pressure - should be 14.5 psi. You may find it up around 17.5 psi. 2. Problem may be caused by a faulty check valve in the return line. This check valve is located at the end of the return line in the fuel pump and fuel gauge sending unit assembly in the gas tank. 3. Check for the correct fuel pump. A high pressure pump that is easily interchangeable with low pressure pump could cause this problem. Visit our Resource Library for available downloads