Quote Originally Posted by maronielb View Post
I see, i don’t think my neighbor cares to install one, he just wants to fix his truck. It’s probably his 02 sensor honestly
If it smells rich out of the pipe and the O2 is saying it's too rich, I'd say there is a rich condition, and replacing the O2 is kinda like shooting the messenger.

That's why I suggested checking the fuel pressure, if it has been cranked by a previous owner, that could make it run rich. An injector not closing could also, another thing that could cause rich condition is coolant temp, but it was reporting operating temp, so that's unlikely.

Only other thing I can think of that would cause it to be too rich, is if someone has put larger injectors in it, perhaps from a 454.

I usually approach diag with what easiest and cheapest first, at this point the fuel pressure would be easiest to check on his truck, and I think O'Reilly has a rental tool that would work, I have used one before, also making it cheap.