Simple question is the original fuel cap vented?

The cap is not vented. There is a small vent on the sending unit on top of the tank. If you suspect a plugged vent you can check by simply leaving the fuel cap loose, as long as your not driving in dusty, muddy, or rainy conditions

I bet I have a clogged rollover vent. I fill the tank until I see diesel and never have a leak, so the float must be stuck and I get a vacuum. I am going to drill a 1/16 inch hole in the cap.

let me know if it works i clean my vent last year. I did it in the late summer and now I'm back to it have pressure when I take the cap off. All ways wonder if anyone ever made a cap with a vent i would buy one. Tired of cleaning mud off the top of my tank from hunting season

My fuel cap was busted so I replaced it and now when I open it to fill the tank, I get a big vacuum. My tank is not flat or bulged on the bottom but its kind of shrunk in a little, its been like that since I have had the truck though.

Watch your fuel pressure improve also. Just drill the hole thru the white underside only in the bottom of the cap. Drill in between the little wheel spoke looking things.

Watch your fuel pressure improve also. Just drill the hole thru the white underside only in the bottom of the cap. Drill in between the little wheel spoke looking things.

Well, I put the 1/16 inch hole in the cap and tested it. Comments welcome on plugging the rollover hole

I plugged mine since I have my own custom tank vent. The Rollover valves seem to be unreliable for some. Occasionally you hear about someone with a collapsing tank. Just a piece of hose with a bolt clamped in the end will plug the valve.It's funny, on the one day I decided to really top off the fuel my rollover valve decided to squirt about a quart of fuel before I got it stopped.

Strange... My truck spend most of it life in the dirt and mud of Idaho. I never had a issue with the tank vent clogging or plugging. I would consider cleaning the tank vent with a small drill bit in your fingers and a bit of compressed air. I really don't like the ideas of drill holes in the fuel cap I would rather fix the actual problem that band-aid it. So like the current tank vent a guy could clean it out and then add a piece of vinyl tubing to it and tuck the other end up in the bed cross bar to keep it clean. There is so many other solutions that drilling holes in the fuel cap.

Anyone ever though about running a vent up and drilling a hole in the steel plate by the fuel cap. I wouldn't think that would be to much of a pain or would it vent fuel on rough roads.

I think it would vent fine but the chances of getting water or other liquid in the vent tube is high. That why I mention the bed cross member tube low chance of water enter then. Kind of like snowmobile fuel tank vents if you look at it it starts at the top and wrap completely around the tank back to the starting point. This system prevent fuel from leaking out highly unlikely to draw water in.

Mike, you are right about running a tube up higher to a cross member to avoid the dirt clogging the vent. Much better than drilling the cap.I don't think its a good idea to push anything inside the rollover valve though because isn't it some kind of flapper in there? It lets in air to vent but won't let fuel out in a rollover wreck?

well i guess on Monday i will drop my tank out and see what i can red neck up. I need to get the mud and sand of the top of the tank anyway. Will give me a reason to give my truck its once a year power washing.