I have a 2006 Chevy Commercial Cutaway Van with a 6.0L Gas V8 (Similar to a Express 3500 and Chevy 3500 Truck) , the Evap is incomplete. I have driven over 50 miles and still it doesn't complete. There are not any pending codes on my OBII reader. My OBII scanner cant force a Evap test. I plan on buying a new gas cap tomorrow.. Any Ideas? (Thanks in Advance)

 

It takes a bunch of certain conditions for the EVAP to clear. Like fuel level between certain values, and start-up temp below certain level, highway miles, etc. Here in CA, EVAP is the only one monitor that is allowed to be incomplete in order to pass smog test. Probably same in TX?

 

if the monitor has not run and failed...no sense to buy parts. the conditions for the monitor to run have not been met. Find out the conditions needed to run the monitor.
As artie said...fuel level must be between 25 and 75% or it will not run. Some models are temp dependent and will not run if to cold out....that is why you dont get evap leaks in the winter...the monitor doesnt run...hence the allowance for evap monitors not needed to be complete for state testing.

 

I had to replace the fuel cap on my '05 Equinox, and was told that it could take 75 to 100 miles to clear the code, without a manual method. of clearing it In other words, it may just be the system being slow.

 

you can clear the code instantly with a code reader, the monitor will read incomplete until the evap monitor runs.... either pass or fail. miles driven has nothing to do with it...the condition to run the monitor must be met during a trip for a monitor to complete.