Fuel smell in cab
 

When i drive my truck hard i get a strong smell of raw fuel in the cab. I have changed the plugs and then after about 100 miles i rechecked them with a torque rench. The smell was there before i changed the plugs. Does the fuel pressure increase when you floor it? If so can i pressurise the fuel system with out the engine running to check for leaks?

Evap purge valve possibly stuck open?

With the key on the fuel pressure should be there
 

If you are smelling it in cab I would think leak is up front . Good chance its orings on injectors . You can pull the whole fuel rail out still connected and put newspaper under it and look for drops . Reinstall using motor oil on orings , Its not a hard job to do . Place some newspaper under fuel filter to see if its there .

The pcm determines the pressure from calculation from pressure difference across the
 

Injector. Not a static atmospheric pressure like a tire . The vacuum created in cyl etc . I am not explaining it very well but I understand the principal .As it sets with key on I think it will run around 40 psi . Torque pro gives you the running pressure from the pcm ..
This system uses a fpdm module on rear axle, the various inputs lets it make a decision to run fuel pump . This eliminates need for a return line or fuel pressure regulator . There is a sensor on the fuel rail that is vacuum assisted to sense acceleration , This sensor feeds fpdm also ,it has a gasket so that is a potential leak point .
Fpdm only has electrical inputs . Fpdm is a high corrosion fail item due to electrolysis if yours isn't bad it most likely will be . New ones are on plastic standoffs to prevent aluminum steel contact .
The most common fuel smell complaint is caused by lose plugs as I am sure you checked for plugs should be torqued to 25 -28 foot pounds . If you pull fuel rails change all orings which are available from local box stores . Carefully blow out area to stop trash from going into intake . Motor oil on orings make them easy to plug in . If over 125k mi I change injectors for new not reman . Leaking injectors can damage engine easily . They are a heavy duty cycle part .
I see you had trouble with the vent line on your gas tank could they be related .
If your gas purge emissions system in trouble it should be setting codes .It checks for a leak by applying vacuum .You have a purge solenoid back on the axle ,some guys have had that trouble as well as rotted lines in this system.

Thanks Redfishtd. I will check the lines this weekend. I think i will try and get it on a rolling road so i can look under bonnet while under load. Yes the vent pipe came off a couple of months ago so may be the tank is pressure in it. When i bought the truck about 6 months ago (2000 miles) there was no gas filled cap on! I will also check the control unit on rear axle to see if it is corroded up