Help me understand how this system can work. I have been driving my 87 Volvo with 300,000 miles on it and the fuel consumption on the highway has been down to about 16-17mpg for a while. I have been going through replacing all the sensors and fuel regulator stuff. I finally got to the Coolant Temperature Sensor located in that great location under the intake manifold. During the process I tested both the old and new sensors and the were both good. At this point I went with the new because I did not want to think about replacing it again. Now I focused on the circuit wiring and found I had 300 ohms on the one wire to the connector on the end of the wiring harness. So I began thinking about running a new pair of wires. Somewhere along the way, I began looking at the wires in the harness (all of them). I had long ago replaced the Oil Pressure Sensor wire and the altenator wire (small field wire). Well, I found a number of wires in the main harness that I will reinsulate. This will not be a problem. It will just require a little time, it won't be that difficult for me as I pulled the whole main harness out of the car.

Here is what has me scratching my head. The wiring to the fuel injectors. First, the insulation on both wire was shot and the wires were about 90% bare, so there had to be some shorting. Secondly, I discovered that there are only two wires that feed all four injectors, one brown ground and the other is obviously the power supply. I am at a loss for understanding how individual injectors know when to open. It would seem that this system would cause all injectors to open at the same time. I have searched the FAQs? How can this system work?