I've been tinkering with my ranger and I've found something interresting if I bypass my evap and put a throttle valve in line from purge system to the manifold I can regulate a vacuum on the tank the fuel cap breaks vacuum about every 20 seconds it makes a deep groan sound but doesn't seem to be damaging anything my ign gage jumped up to around 28-30 and I'm getting about 32 mpg highway I'm pretty stoked think I'm using the vapors of the top of the tank and the computer is cutting back on the injection rate. Any thoughts on what I'm doing hopefully I don't damage anything