There are many indicators that the regulator of your vehicle would indicate if they are not working properly. It is important to note that they are a very important tool for your pressure tester so you must take good care of it and replace it if it is not working. If there are any misfires, leaks, or black smoke then you must change the regulator. To easily inspect if there is any leak or not, your product must have piston rings, exhaust valves, and head gaskets in the fuel pressure kit. When there is a misfire or decrease in the power, acceleration, and efficiency of fuel, then it indicates the failure of the regulator and will disturb the fuel pressure of the vehicle. Also, due to the fuel leak, the regulator of your vehicle is affected which leads to the emission of black smoke from the tailpipe. And the fuel smell will tell you that the failure of the regulator is due to a fuel leak which may adversely affect the performance of the engine in your car and also reduces the mpg. As the regulator is an essential component of your pressure tester for fuel pump, you must take good care of it and if you find any fault then you must get your vehicle check by the technician near you and get it to replace.