What does a fuel damper do, and what would happen to it if someone were to actually screw in the screw in the back.? Just hypothetical, you know.

 

In electrical terms, it is like a capacitor, or in mechanical terms, it is like a shock absorber. It dampens out the pulses of pressure in the fuel rail as the injectors are turned on and off. Not sure what the internals l9ook like, but I would guess it is a spring loaded piston and the screw probably sets the pre-load on the spring.

 

The screw is just supposed to sit in the hole. It is actually not supposed to "screw" in. Go figure. Anyway, I'm wondering if by screwing it into the hole in the back if I widened the hole and that would cause an overabundance of fuel pressure and then cause the truck to run rich.

 

The damper damps out pressure pulses by smoothing out the low and high spikes. The pressure regulator controls the pressure. Kind of like springs and shocks on your axle, the springs set the ride height, the shocks damp out the bounciness.

Not sure what damage if any can be caused by messing with the screw. Leaking would be a sign of failure. You could check the fuel pressure if you are concerned about that. I run an electornic pressure sender on my fuel rail:
- http://www.4crawler.com/4x4/CheapTri...rPressureGauge

And make sure the vacuum line is connected to the fuel pressure regulator, if that is messed up, you will get too high a fuel pressure (most of the time):
- http://www.4crawler.com/4x4/CheapTri...ine_Pix/8.html