About a month ago I changed all 8 plugs on my 2005 2V 4.6L F150.

The other day I was driving home and felt the engine vibrating a bit as if one or more spark plugs were not firing.

I googled the problem and it seemed that most were attributed to spark plugs backing out.

I checked all 8 plugs today and all were tight. However two of the coil on plugs 7mm bolts were not all the way tight allowing the COP to be loose. I tightened those up and it appears, so far, that the vibration has went away and the fuel smell.

Time will tell.

 

Maybe take a look at the fuel injectors if you smell gas again. The loose bolts would not have caused a gas smell.

 

Thinking that with the coil not firing, the injectors probably dumped fuel into the cylinder, and that's where your raw fuel smell was coming from.

 

That is what I was thinking too.
If it continues I will check the fuel injector O-rings.

 

Fuel smell usually lose plugs . What kind of torque are you using. Yes it could be fuel rail problems. Yes you could be correct the cops are subject to a loose connection .
Corrosion on terminals a big problem . Good luck with her.

 

I checked all the plugs and none were loose. I used a torque wrench (where accessible) and I believe I used 20 ft-lbs.

 

We have been using 25 to 28 foot pounds . But all plugs should be torqued the difficult back ones are the most likely to need it . Its not that hard you may have to have some different sockets etc or a smaller torque wrench to get to them. Its not as bad as years ago they made engines that the back spark plugs could not be changed without pulling engine.
And for years some bad shops would not change plugs that were hard to get to and they said they did. If they got caught they would say- oh -we fired that guy .
Good procedures on changing plugs is very important in aluminum heads . You must clean out real well and start the plugs in a good ways by fingers and it should feel right . Cross thread one and you are in trouble . Heli coils don't work in this application .