Fuel tank issues
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Fuel tank issues
hey there. I have an issue that cropped up today on my 74 highboy. I noticed some fuel leaking from the cap. I took the cap off and fuel shot out. Tank was only about 3/4 full. Any idea what could be causing this kind of pressure. The filler neck is vented. My first thought was that it might be plugged. Doesnt seem to be though. Another possibility...The guy I bought it from has both a mechanical and electric fuel pump. The thing is running great but wonder if maybe the electric pump is not working and building some back pressure? I dunno, just throwing things at the wall to see what sticks. Any help is much appreciated.
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fuel cap is vented. It should be, right? I just bought the truck a couple weeks ago but have put maybe 300 miles on it. Not had the problem until now. I would suspect the wrong cap would have given me issue pretty quickly, right?
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That I'm not 100% sure of, but were going thru the same issues with other cars with this new fuel.. For you chevy lovers 
- Beat the Summer Heat Blues... TPI Fuel Vapor Lock - Third Generation F-Body Message Boards
- Beat the Summer Heat Blues... TPI Fuel Vapor Lock - Third Generation F-Body Message Boards
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Joined: Nov 2011
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The fuel fill is usually vented to the tank. The tank needs a vent also. There were different systems used as original but often a vented cap is required.
Good idea to make sure you have a vented cap. Also vented caps sold today have pressure relief vents. They can build up a good bit of pressure or vacuum before they open. A little pressure is OK but vacuum can contribute to vapor lock which is no good.
The fix I and many others have made is to drill a small hole in the cap. 1/16" will do it. Just have to locate the hole so it actually vents to atmosphere.
Good idea to make sure you have a vented cap. Also vented caps sold today have pressure relief vents. They can build up a good bit of pressure or vacuum before they open. A little pressure is OK but vacuum can contribute to vapor lock which is no good.
The fix I and many others have made is to drill a small hole in the cap. 1/16" will do it. Just have to locate the hole so it actually vents to atmosphere.
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