I don't know if this pertains to your situation or not, but you mentioned an electric fuel pump. I'm wondering what psi the pump puts out. I bought one that put out around 6 psi, and it was flooding the carburetor until I installed a fuel pressure regulator that reduced the output to around 3 psi (I'm going by memory here).

As I said above, I'm not sure if this would affect the whoosing noise or not.

Pat O'Connor

I,ve got a 54 , i have owned it since 1989, (actualy its a DeSoto Dipllomat which is purely Plymouth apart from the grill ,badges and minor trim changes)it does have a non vented fuel cap , which is original,and no i have never heard a whoosh sound when removing the cap . the only problem i have found is where the filler is situated it makes for slower filling the tank.

Yeah, I opened the cap & pushed an old speedometer cable down through the vent tube to make sure it was clear.  I was able to go all the way down to the tank, and the end of the speedometer cable was wet & smelled like gasoline, so the tube is clear!  According to the various official Plymouth books & pamphlets I have, the 1954 models don't have a vented cap, just the vent tube, but it does seem strange that there is so much of a vacuum created by just the fuel pump.  I'm afraid of collapsing the gas tank too.  :o

seems to me the 54 should have a vented cap.  If not, then the vent is in the tube that goes to the tank, you should be able to see it with the cap off.

I am surprised you have not yet collapsed the tank.  It is amazing what the weight of the atmosphere can do.

I don't know how the '54 models have their fuel tanks vented, but however it is, yours seems to need repair.

I vaguely recall on the 1960s Mopars that I once owned that even if there was a separate vent from the tank to the filler you still needed a vented filler cap. So that would be the first place I'd look on your car.

Alright my friends, I'm new to Plymouths, so there are a lot of things I'm don't know yet about my '54 Belevedere.  I do know that it has an electric fuel pump, and I'm not sure if the "original" one works, but I do know that the fuel line goes to it and out to the carburetor.  Now, whenever I open the gas tank to fill it, there is the "whoosh" sound of air rushing in.  My question for now is that Okay?  I know that Plymouth added a vent line to the '53's & 54's so I was surprised when I heard that noise. Any help will be much appreciated, and I'm sure you'll see a lot more posts by me asking various questions.
Thanks.

PS: I do have both an original Owner's Manual and a Service Manual, but some of these topics just aren't covered since they are sooo basic.  Unfortunatley, it's been too long since I last drove a 6 Volt car, my current "old" car is a 1967 Beetle.

George