Bdstone

So do all 4 injectors fire at once or are they fired in pairs?

Hi, New to this forum and this is my first post. Looks like ther are some really knowedgable people on this forum. I have a 1987 GL 10 turbo 4WD with multi point injection. I did a valve job and had the car running good for a couple of days. Then I had gas flowing out the tail pipe with the engine off. Found the injector connector problem and fixed it. Put on all new connecters at the injecters. Problem is I do not get a ground signal to two of the injecters. I gave it to my mechanic and he thinks it is the ECU. I tried a used one and another that was supposed to be rebuilt and still had the same problem. I have the factory manuals but can not find what tells the ECU when to fire the pairs of injectors. I doubt that three ECU's could all have the same problem. Check continuity on all the injecter wires back to the ECU. Even open the harness all the way from the engine to the ECU and found nothing. Could it be crank position sensor ? Stumped on this one. Bruce