I have a 2000 Excursion V10 that started getting a very strong fuel smell in the cab. Its not a California Emission so no EGR. I noticed it was coming from the engine compartment. After some reading I thought it might have something to do with the Vapor Evac system and even though I couldn't find anything wrong with the vapor purge valve I replaced it anyway. This stopped the fuel smell coming from the engine compartment but I the engine is now running rich and I'm getting a fuel /exhaust smell in the cab.

 

It really started having problems a few months ago with it using a lot of oil. I change the PCV valve and that seem to limit the oil use. However shortly after that I noticed a loss of power and the smell in the cab as well as having problems starting. I found that the CAT was clogged and cut it out and it now has a straight pipe in place. That fixed the starting problem. I haven't replaced the CAT because I don't want to just put a new one in to get it clogged as well. Also It has never given a Code.
Other things I've done:
* both exhaust manifolds had broken studs. I replaced the studs and gaskets.
* Replaced both O2 sensors while I was doing the manifolds.
* I pulled the connectors off of the coils one at a time and all seemed good.
* Checked the fuel pressure and didn't see any problems. I had a new fuel regulator though and just replaced it yesterday which made no changes.
* Replaced the gas cap too, Seal was dry rotted.
* Replaced the hoses near the fuel filter for the Vapor system as well as in the engine compartment. I couldn't find any leaks but they were in pretty bad shape.

Yesterday after I changed the fuel regulator, I drove about a 1.5 miles to Whataburger as a set in line in the drive thru it started getting a noticeable shutter. Like a slight misfire or vacuum leak. I've sprayed started fluid around and so far have not been able to find a vacuum leak.

I don't have a scanner that graphs but it does give some data. The LT fuel trims look good. At Idle LTFT1 is 0.7 and LTFT2 =3.1. The short term starts out around 0 but after I drive for while it seems to jump around some at idle. After driving today some as I set in the driveway idling both STFT were trending down to -5 to -11 range but moving around. The CALC Load % is a 50 at idle is that high? The O2 sensor appear to be cycling properly.

 

If the engine is running rich after you changed that purge valve, then something else is going on.

You have a lot of gas in the charcoal canister for some reason. Do you overfill the tank?

 

MAF is reading around 8 gr/s at idle is this a good range?

I have overfilled it before but I've had it several years. Why all the sudden would that be a problem unless maybe the check valve on the tank has gone bad. I looked online and couldn't find the check valve. Guess I'll have to see if the dealership has them. I think I should replace the vapor lose from the tank to hard line seeing as bad as it was in other areas. I pulled the hose off the charcoal canister yesterday and really could smell anything that I thought was out of the ordinary, but still could be an issue. I also read about gunk build up on the throttle bodies so may need to look at that, I know I had a chevy 5.7 that the IAC valve was not closing because of build up and causing problems.