Whie sitting in garage, the gas seems to evaperate out of all three cars. There's is no leak.
It does evaporate. The tanks are open to atmospheric pressure by way of the vent hole in the cap. Standard gasoline has a vapor pressure (RVP) of about 7psi @ 40C. The vapor has to go somewhere. This is why they tell you not to store gasoline in an enclosure that may contain an ignition source. (Hot water tank, furnace, etc.) The Model T gas tank is nothing but a gas can under the seat.
Modern cars have a closed system.
look for a VERY small leak. I have seen this before, hard to find. Dan
Ken and Dan are both correct. Gas will certainly evaporate from the tank. However, I have experienced a slow leak that a drop would evaporate from the floor before the next drop would fall.
My wife has a bionic nose, and I can tell you from past experience that indeed it does evaporate AND emit odor while doing so. Most of us won't smell it, but by gosh she sure can! I need to hire her out to the gas company to be one of their sniffers!
Put your hand on the shut-off valve/sentiment bulb and see if it is wet. It may be leaking slow enough that it evaporates off the sediment bulb before accumulating and getting heavy enough to create a drop and fall to the floor.
Note there are many places on the sediment bulb where it can leak:
1) where it screws into the gas tank
2) either side of the shut off handle
3) around the circumference of the screen housing
4) where the gas line attaches to the screen housing
5) where the petcock screws into the sediment bulb
6) at the either side of the petcock handle
7) at the petcock opening
Also - you'll know if you have a leak, no matter how small, if you walk into the garage and smell gasoline.
How big is the loss? If you can tell it's probably more than evaporation. Agree with Tim: even if I didn't smell it She would.
My sediment bulb seems moist most of the time so I know I am getting evaporation. My garage smells like fuel so we keep a window cracked open to help, and then air it out every so often.
You've pretty much answered your own question Marv.
Sediment bulb should not be wet unless you have a leak.
You've answered your own question Marv. A wet bulb, carb bowl, petcock or whatever isn't evaporation. It's leaking.
Got it. Sometimes the obvious escapes me. I need to just crawl under the T and turn the sediment bowl off, see what happens then. Thanks Charlie. Hope this helps the others on this topic. If still moist then leaking at the tank. It seems moist under the gas line.
It was the gas line connection that was leaking. I took the sediment bulb off a few months ago to reseat the handle/shut off valve. That worked when I used some abrasive soap and pushed the handle in and wiggled it back and forth to create a new seat. Hope this all helps Rfbuff. Just a little tighter turn on the gas line connection and the fumes began to disappear in five minutes!
Thanks to all for stimulating me to rethink why I was smelling fumes. You all are the greatest!!!