I HAVE A 99 3500 WITH AN EDGE COMP AND DD3 INJECTORS AND I HAVE FOUND THAT IT WILL SOME TIMES BUILD ENOUGH PRESSURE OR SUCTION IN THE TANK TO CREAT A WHISTLING SOUND FROM THE FILL CAP

 

Depending on you POV, this could put a big on or else ! I wonder how much air can be safely vented through the cap to relieve suction? The rust free nature of our Poly tanks is cool, but I always wonder about durability. Then again, the Poly is more forgiving than a thin sheet steel tank... Reduced capacity from suction implosion would be a BAD THING!

 

the way they test the gas caps out here for inspection anything other than what they give ya will not pass, might have to revert to a running cap, one with a better vent and an inspection cap, stock if your state? is strict... fill out that sig so we know hwere you are and what ya drive, lot easier than typin it every time..... also just a thought last sec have you tried not tightening the cap all the way? just enough to keep the fuel form sloshing out but will vent like you need.

 

I just set my cap on the neck and that's it. Don't know if the tank pressurizes or not but if it does, it goes right out.

 

There is an old bullitin that had you inspect the roll over valve on the tank and see if there is a shipping plug on it. Some were not removed on assembly and created a vacuum in the tank. It's just a rubber plug on a plastic nipple. If it's there, get rid of it.

 

My truck doesn't have the plug, at least not that I can find, and I still get suction on the tank. Anything I should do, or any ideas on finding a vented cap?

Thanks,
Chris

And sorry to hijack the thread, guys!!

 

I had seen the bullitin years ago, but only ran into a truck this year that had the tank sucked in at various points. Crawled under it and found the vent plugged. On yours I would probably just use a small drill bit and make it vented.