Hello, I bought a 1995 2500 turbo diesel a week ago. When I bought it the guy told me that there is a helper pump that delivers diesel to the injector pump and when you turn the engine off you can hear ticking for 3 seconds this is what tells you that it is working. The first day I could hear it but now i cannot. I have been driving it kind of hard. Does anyone know what the problem could be or if there is one?