Thank you Mr. Wayne for the videos and Mr. JO for the information. I should grab my jacket and go out to the shop and see what I can put into practice, but unfortunately winter is hanging on. Just had 4 days of 55 mph winds and now it is only in the 20's. The wind blew some tin off my old barn and blew the window out of my shop. So I have some unexpected project come up before I get back to work on the truck.
Before my high-bred hook up, when running on woodgas, I always had the air valve almost totally closed. If I turned the fuel pump on it would flood the enginel. ( I guess there wasn't enough extra air to feed the gasoline.) I never tried it but I suppose I could have opened the air valve and then turned on the fuel pump. That seems like it would have made me running on petro and not pulling any woodgas.
I remember Mike LaRossa came up with his tbi woodgas truck and he was so happy with how it was running. On the way home he realized that his gas gauge was headed to "empty'. He thought he had the fuel pump turned off but the injectors were still working. He concluded that the tbi was siphoning gas from the tank and the injectors were injecting it into the engine. Could it have been that the O2 ( lambda reader) had taken over like you are saying. I don't know how he had the fuel pump and injectors wired up, but I do know that every since, I have always shut off the fuel pump AND the injectors when running on wood gas. TomC