I like that vw conv idea. Sort of like the commercial on tv where the guy wrecks and pulls the spare from the trunk.

Did You see Chris Angel's jump of the Grand Canyon recently. What a waste of an awesome 3 wheeler. Would love to have one of those in the back of the Rover.

 

ok I always thought the air escape sound when taking off the gas cap was a BAD thing..

Mine doesn't do it.. Hell no NEW vehicle I have ever had did. Now my 1990 nissan with mold growing on the south side [moss] does it.

 

The fuel system is designed ( I believe) to maintain the pressure. The fuel pump does run at approx 36 PSI or so right? Nothing that I am aware is supposed to vent it off when it is shut off.

I admit, I was surprised by the strong hiss when removing the gas cap the first few times after replacing the fuel pump assembly and gas cap, but I am sure the strong hiss is a good thing, not a bad thing.

Guys does yours have a healthy hiss?

 

Nope.
Neither before nor after I replaced my fuel pump.
Nor does any other car I have ever driven.

 

I really doubt there is any mechanism to make this a pressurized fuel tank. Most aircraft aren't even equipped that way. As the fuel is pumped out of the tank, the volume that the fuel was occupying has to be replaced by air, which ought to be equal to atmospheric pressure. So if your gas cap is hissing when you open it, that may be a bad thing, meaning air is rushing IN, not out. Meaning something isn't allowing your fuel tank to vent correctly.
My parents had an old mini-van that had this problem. We'd be driving down the highway, and the engine would start starving and losing power. Someone would get out, crack the gas cap, HISSSSS, the fuel tank would equalize with atmosphere and off we went...

 

The more I read about the hissing issue in general, it also seems to depend on weather (hot or cold) and how much fuel is in the tank (air to gas ratio).

 

mine has peeed on me when its raining hard, it has dripped on me when I'm under it, but it has never hissed at me, It does have a P1176 issue I can't seem to solve (yet), but no hiss.

 

Well I could be wrong, but by virtue of the return line from the engine compartment to the fuel cell, don't we in effect have a closed or sealed system if there are no leaks?

Seems to me the fuel pump operating pressure would thereby pressurerize the entire system including the air spec in the tank would it not?

If you crack open the external fuel filter line, will get sprayed, right? It is pressurized.

If you check the valve under the hood, it will show pressure if all is right.

If you any fuel line connection, you will vent the pressure.

Seems to me it would hold some pressure. I know when I loosen it to fill up, it has a strong hiss, not a suction as was suggested.

 

Then fuel pump pumps the fuel from the tank to the engine at lets pretend at 80psi, the fuel pressure regulator drops that down to a usable 40psi (pretending again) and the excess fuel is returned to the tank.
The excess fuel sprays the fuel pump to cool it.
The fuel pump pumps liquid not air, it should be a zero sum game, it removes the fuel at 80psi and it should return at 80psi.
Except the fuel pressure is going to drop off after it is sent back to the tank.
While you only need 40psi at idle you need more psi at higher rpm so less fuel will get returned to the tank.
Your fuel filter holds pressure after shut down because the fuel psi regulator is keeping the fuel from getting past it.
The fuel pump pressurized the fuel system and is designed to hold psi, so it is like holding a finger over each end of a soda straw filled with pop.
The fuel psi regulator is one finger and the fuel pump is the other finger.
Poke a hole in the straw and the pop leaks out, loosen the fuel filter and fuel leaks out.
Make sense?

To know for sure if your fuel tank is releasing pressure or taking it in you will need to do a smoke test at the gas cap.
If the smoke is sucked in or blown away will tell you which it is.

There was a recall on DI and RRC fuel tanks back in the '90's because they would not vent properly and as the fuel level dropped and the extra space was not being filled back up with air it would collapse because it is a plastic tank and it would crack and leak at the top seam.
The signs of this were a hissing sound when opening the gas cap as well as the truck stalling out on long trips from fuel starvation.
Remember that you also have a filler neck vent tube to let the air out as you put fuel in.
The gas tank needs to suck in air while driving, if not it will collapse as the fuel pump sucks out all of the fuel.
The EVAP system is a one way valve, it lets air in but no fumes get out.

I threw out alot so I hope it makes sense.

 

OK, if you say so. I know my fuel tank was replaced as verified by A&L LandRover.

I'll hush about the hiss.