Ran fine last week, started truck up yesterday to keep battery charged, ran rich, I changed the regulator about 3 weeks ago with one I had sitting around, I tested it by sucking on the hose and no change, it seemed like a solid vacuum, no give, I thought it froze from the cold but it had a little heat, that is the only thing I changed to justify why it is running rich. I did not put a fuel guage on it to check it as it was 15 degrees out when I started the truck.

 

Yep,sounds like you need to pull codes. When was the last tune up? Is this a test?

 

How do you know it ran rich? fuel coming out the exhaust?

 

Mine is eating fuel like a dope feen .... Which sucks the 4.9 is not the best for mpg but a few people I spoke too said fuel regulator . I had the check engine light on intermittently 3-4 times which if it was dumping fuel would throw the o2 sensor reading all crazy . I'm going to order a new one tomorrow at work ok my account from my local ford dealer ...hope it works

 

It won't spit fuel out the tail pipe but it will burn your eyes out if its running that rich .. And burn fuel way quicker then normal consumption

 

It can be a lot more to it than just a o2 sensor.