What the hell's going on here?

Last week I bought a 70 Valiant 4 door, and in the process of servicing it I found out that I can't put gas in it! It takes about 3/4 of a gallon before the fuel backs up in the filler tube and comes shooting back down the fender!

I noticed that someone had plugged the vent line that goes to the engine bay, so I unplugged it and left it open to see if it cured it.

It didn't do anything. The fuel still won't go in to the tank, even if I fill it slowly. It gets like a gallon in and backs up. The fuel doesn't even look like it's going down, either; it just sits in the filler neck.

Are there any other lines in the tank that vent it to the outside besides the one going up to the engine bay?

My fuel gauge reads E right now, and I've seen it move since I got the car. If I in actuality had a completely full gas tank (that could be why the gas backs up), and the float had a hole in it, would the gauge still fluctuate back and forth?

Also, is there anything physically in the way of me putting gas in the tank, like a swinging door or anything like that, or is it a straight shot to the tank?

Thanks guys, I want to drive this thing, but the gas that's in there can only take me so far!

Nick,
Needs to find an answer...

The gauge sender could be flaky and causing empty or fluctuating readings when you actually have a full or near-full tank. Sounds like someone monkeyed with the tank vents without understanding what he was doing; this can certainly louse-up your ability to fill the tank. Get on hands and knees and peer at the tank -- in extreme cases of vent tampering, the fuel pump's suction can actually collapse the tank!

No flap doors or anything in the fuel filler neck; that didn't start til '75, and then only on unleaded-fuel-only cars.

With the tank vent line running up to the engine bay, it sounds like your '70 is equipped with the evaporative emission control system (mandatory in California for '70, optional elsewhere, mandatory everywhere for '71). These '70-'71 tanks have two or four vent lines (one at each corner or one left and one right) leading to a vapor cylinder in the trunk, usually found snugged up against the left rear wheelwell. There's also usually a vent line leading from the tank itself to the top of the filler neck.

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