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I recently filled the stock tank of my 66 F250 Camper Special, and after a day of driving to work and back (about 20 miles), parked it in the back with the nose slightly up, and leaning a bit to the driver's side. I came out the next morning, and smelled gas immediately. Sure 'nuff, it's running out of the inlet, and down the side of the truck! So, I run down to my neighborhood parts store and pick up a replacement cap - got a locking one for good measure. And not some generic one - this is one that was specified for my truck. I suspected right off the bat that it wasn't going to do the trick - it didn't look to be any tighter a fit than the original. Sure 'nuff - came back out after being parked for an hour, and this time the gas is a steady stream, not just trickling down the side. Any advice on how to resolve this? I notice that Dennis Carpenter has locking replacement caps, but at $30 it's twice what I paid for what I have, so I'm not willing to jump into that unless somebody can tell me that's the likely culprit. As always, thanks in advance for your help! - Pat
My '66 F-100 did the same thing under similar conditions on a hot day. I guess the answer is to avoid topping off the tank or always parking the truck with the filler on the high side when the tank is full. Hot days simply cause the fuel to expand.
THe newer blends of gas (oxygenated fuels) expand more in the heat. It's all that O2 they add to make it burn cleaner. I would leave some room in the tank when you fill it. Go up to about the top of the tank and not into the filler neck. Try that before you spend big $$ for a gas cap.
Most station now have sticker on the pumps warning you not to "top off" the tank. For the very reason above. I always top off if I'm leaving for a trip but around town, just dump in until the nozzle shuts off when on high. Then push the handle all the way in and slowly squeeze the trigger. When it shuts off, your full. No overflow.
I had the same problem on my newly painted '64 F100. But I had the added agravation of the gas pealing the paint all the way down the side of my truck. As it turned out, my paint and body man (who paints as a sideline) had not removed the filler neck grommet before painting and the gas got under the paint. It sure made an ugly blemish on my new paint! The guy did eventually agree to repaint the area and replace the old grommet with the new one that was still in the box of parts I had provided him for the job. The moral of this story is ... you get what you pay for. I paid for an amateur paint job and that's what I got.
I also had the same problem on my newly painted '64 f100 which also damaged my paint. The gentleman who painted my truck repaired it for me and said it had also happened to him. I had a new gas cap when it happened but when the pressure builds its gonna go somewhere. I no longer fill to the max unless I'm going to be driving it immediately after. Is it possible to install an overflow line?
I wouldn't put a overflow on that as you could be creating a fire hazard. I would just not fill it as far up each time. With the new type gas out there it has more oxygen in it, so it expands more when it gets warm.