Hey all
I have a 89 formula with a 305 tpi that's been having some poor running and idling conditions. Today I started checking ecm grounds and other things. While doing so I noticed that with the key on the fuel injector connectors have power on them. I know that one side is connected to the fuse box and should have 12 volts on it with the key on. However the other side of the connector also has 12 volts. I thought that the ecm was open and would not show anything until it is pulsed/ pulled to ground. Is this correct?
Also I noticed that my fuel pressure will sometimes drop off when cycling the ignition switch. I can turn the key on and the pump will build up pressure and it will stay good for a while. Sometimes when the key is turned on the pressure builds until the pump kicks off then instantly drops from 40 psi to 0. Could any of this be associated with the injectors/ injector circuits?

 

This should be moved to tpi !, If your fuel pressure is dropping off that fast you have either a faulty frul pump or dampner, bad regulator or leaking injectors.

 

When you have injectors still plugged in, you will see 12V on the injector signal wire.

The reason is that the coils in the other injectors will allow voltage to be seen on the injector trigger (ECM) side. So what you are seeing there is normal.

 

The fuel pressure was a secondary question. My main question is about the injector connector having power on both sides. I was simply wondering if the power on the connectors is suppose to be there and then if not could that cause the random fuel pressure problem. The power on both sides of the connector is consistent unlike the fuel pressure.

Thanks

 

Ok yes that makes sense. That's what I was wondering about. So it seems my fuel pressure drop is independent of the injectors being held open. Thanks a lot I'll keep digging.