I have an 86 s10 with the 2.8 tbi. I'm having an electrical/fuel issue. I hooked a Noid light upto my injector connectors and it won't light up at all. But when a Multi meter I have constant 12v supply to my 2 hot wires. I'm not sure what the other two wires are suppose to do. Are they a ground or return? If they are a ground I am Gettin no ground signal. Any ideas?