True vented gas caps have the vent hole and a little check valve to prevent gasoline from sloshing out. Vented caps are so stamped and are pretty much available at auto parts stores. Authentic caps should be readily available from salvage yards. I'd do a quick visual check of the tank. I can see where pulling a deep vacuum on the tank, then relieving it quickly could damage a fuel pump. Careful inspection of crankcase oil would be good idea to see if fuel flowed there through the damaged fuel pump. I'd not start the engine until the contaminated oil was changed out if that was the case. Seems like I've seen decals inside gas doors specifying vented or non-vented gas caps. Rich Barber Brentwood, CA From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Lindsey Fuller Sent: Tuesday, August 28, 2012 7:22 AM To: Ron Waters Cc: Chrysler300@xxxxxxxxxxxxxxx; cpaviper@xxxxxxxxxxx Subject: Re: [Chrysler300] 'Negative' gas tank pressure I believe your conclusion is correct Ron. He should get it vented quickly. I actually had a replacement tank on my E collapse in all 4 corners from this negative pressure after redoing the whole fuel system. Would not have believed this possible unless I had seen it happen. 1/8" hole preferred solution over installing a new tank, Lindsey in Winnipeg. ----- Original Message ----- From: Ron Waters <ronbo97@xxxxxxxxxxx <mailto:ronbo97%40comcast.net> > Date: Monday, August 27, 2012 10:28 pm Subject: Re: [Chrysler300] 'Negative' gas tank pressure To: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> , cpaviper@xxxxxxxxxxx <mailto:cpaviper%40comcast.net> > He needs a VENTED gas cap. Or just drill an 1/8" hole in the top > of his present one. > > Ron > ----- Original Message ----- > From: <cpaviper@xxxxxxxxxxx <mailto:cpaviper%40comcast.net> > > To: <Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> > > Sent: Monday, August 27, 2012 11:18 PM > Subject: [Chrysler300] 'Negative' gas tank pressure > Was at a local cruise-in this evening, and visiting with fellow > 300F owner, > Frank Troost. Frank mentioned a problem he had last Sunday with > his '57 > Adventurer coupe. He said the engine seemed starving for fuel, > the glass > bowl fuel filter wasn't filling with gas, and when he un screwed > the gas > cap, there was a huge 'whoosh' of air into the tank, and fuel > flowed to the > engine. His fuel pump now seems inoperable. > > > > Does this sound like a gas tank venting issue? I read the > archived emails on > 'positive' gas tank pressure, but this is the opposite problem. > > > Thanks, > > Noel Hastalis > > Burr Ridge, IL > > 300F > > [Non-text portions of this message have been removed] Lindsey Fuller 300 E,F [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: Chrysler300-digest@xxxxxxxxxxxxxxx Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/