Hello:
I'm liiking for any input on this situation:
'04 1500 Suburban, 95k+ miles, & it is well loved by my wife and myself.

'Tighten Fuel Cap' warning; wife goes to local Chev dealer. diagnosis is 'bad gas cap' ; <$50 & out the door quick.
Situation repeats in a few days; same solution, but now 'N/C'

Then a few days, Check Engine light on. Local shop checks, code for vapor recovery; suggests start off with gas cap. OK, & he puts it on.

Situation repeats; replaces purge valve.
Situation repeats; replaces filler neck
Situation repeats; replaces valve on/near canister.
Few days later (100 miles+/-) 'Tighten Gas cap' & check engine light back on'

Any hints??

 

almost sounds like there is a leak in the vent/purge lines. could be vent line at filler neck, could be the line from tank to motor, or it could be at the gas tank.

 

I've been reading thru a thread here on this problem on a Tahoe!!

 

Johnhlec1 welcome to the forum....
you might try having the system smoked check to help identify the leak

 

I omitted that the local garage did the 'smoke test', between the gas cap (#3);the purge valve; the filler neck; the valve.

Based on what I read at the thread mentioned above, the only thing left is the canister, and the hoses! Back to the garage Sat AM to let him try again.

BTW, this is a very helpful forum, with a wealth of information. Had I found this info before commiting to the local garage, I would have attempted this myself, and the weather is not too good to work outside for the last few weekends.

Thanks to all, and I will continue this forward.