smokinlmm

Ok, so I bought a locking gas cap for my truck. I always have them to keep people from putting the wrong fuel in my trucks. I hide the key in the center console and have a tag on it that tells who ever is driving what fuel type. Now that I explained that....


The first time I whacked on the truck after I installed the new cap it was wayyyy down on power. I didn't immediately think gas cap, who would, so I logged the truck. Fuel pressure was off, I then thought about my new cap so I switched back to factory cap. Violia, bammmm, all power is back. WTF? So I took apart the locking cap thinking it wasn't venting properly, nope still terrible performance. I called my friend who is an incredible tech and he told me that the tank is pressurized and I have to use factory cap? Just thought I would share this tid bit with y'all, I found that odd so I'm going to take apart a factory flex fuel cap and see what kind of magic wand GM has inside it...

someotherguy

Now you've got my attention. I had a locking cap on my 06 SS, came on the truck when I got it a couple years ago. The gasket on it was all cracked and falling apart. Recently I got a few "tighten gas cap" errors and then finally set the P0442 code for an evap leak, so I said let me start with the simple stuff - bought an OEM GM cap for it based on part # lookup through the dealer. Now it seems down on power, noticeably so...and still have the error & code, so I'll have to move on to the evap solenoid and possibly canister, but still.

Richard