A couple of weeks ago the car was driven to the store. It ran normal and well. Within 10 min. we got back into the car and it would try to start but would not run. It is a 1982 VW Rabbit conv. that was built in Germany. It has a 105 CID mechanical fuel injected 4 cylinder gasoline engine. The first think that I thought about was the fuel pump. So I replaced it. Nothing changed. So over the past several days I have also pulled the fuel pump relay and cleaned it, then replaced it with a new one along with the fuel filter. I have pulled the constant pressure regulator and cleaned it. Nothing has changed. I know that the fuel pump is running properly and the fuel pump pressures the lines up. The new relay works properly. I'm curious about the frequency valve located on the back of the fuel distributor. I can't tell if it is working or not. I don't know the voltage it should carry. I believe that it's 12 V. I also don't know what componant tells the frequency valve to operate. Whatever it is, something is not telling the fuel distributor to let fuel go to the injectors. I can say that when gas or carb cleaner is sprayed directly into the air intake, the engine starts and runs fine until it burns off everything that was sprayed in. I also pulled the cold start injector out and it does operate as it should. I am no expert and this is my first time dealing with this type of fuel injection. I'm afraid that I may have just enough knowledge at this point to be dangerous. Any info or suggestions would be greatly appreciated. Thanks.