Hello, Don't stop cleaning the engine. Water is getting into your nuetral switch. I keep my engines spotless. I use super purple and blast away with 1500 to 1700 pounds of pressure. I have been cleaning engines for 20 years the same way. I have never, and I mean never had a problem that air drying would not solve. If someone brings me a car that is filthy it gets washed before I start working on it. There is nothing worse than working on a greasy, oily mess of an engine. The pressure washer is my friend. If you know its going to do it just bring a air tank with an air nozzel and dry it off before you leave. I treat a clean car with way more respect than a filthy one, because I know the owner cares about his or her car. Any good mechanic does, hands down.
So keep your engines clean!