I've got a '75 and the CA gas pumps won't seem to fill it up, and I keep getting gas flowing back out the tank when I pull away, even though the tank is not full. I can get a couple gallons in by going slowly, stopping, waiting for a bit, then filling again. Once I get too close though, I just get clicks - but the tank could still take a few more gallons. One thing that is missing is the little door that pushes open when you put the nozzle in there. Other than that, I'm not sure what could be causing this?

-Phil

I'm inclined to agree with poster GEOF.

I have always thought that the tank has to have a vent from the very top to let air out.

Going with that I have seen them follow the filler tube on the outside or inside. Even with the filler neck at the very top. A tank can still get air bound if the tank is tilted with the neck lower than the other end. Or the neck filled with fluid to cause it to make burping/bubbling sounds. All causing voids.

Tanks are built to allow for some expansion of fluid after filling unless you milk it till its really full and sits in the neck! You know, using a broomstick and stuffing it in!

Of course a vent could be designed to go else where. Example, evaporative canisters on newer cars.

About 1973, American cars started requiring evaporative canister systems. Imports were probably at or ahead of them in order to sell here.

Possible you have a tank with a collapsed metal or rubber line system. With or without a container. On 78's I know they use tanks that hold pressure and use relief valves to canisters. 75's are not that far back!

Food for thoughts to look around?

I had a 1973 145 that had a tube within the filler tube. This tube enabled air to get out of the tank while gas was going in. When this vent tube was not positioned correctly, the tank could only be filled slowly.

In some areas of the country, the gas nozzle is just a narrow metal pipe that fits loosely into the filler opening. Gas fumes that have collected on top of the fuel's surface are pushed out of the tank, into the air, when the tank fills with fuel and the fumes are displaced.
But in many other areas of the country, gas nozzles have a contraption that sits over the entire filler opening -- it's meant to catch those gas fumes and suck them back up into the station's tank, thus preventing the escape of gas fumes into the atmosphere.

The trouble is that sometimes this contraption doesn't work well, and it causes pressure to build up that falsely triggers the filler mechanism (valve) to shut off. This is especially likely if the car's tank's own vent is also clogged, so pressure cannot be relieved. Thus, the tank resists being completely filled.

I once owned a '75 164 (the last years of the 164's), and it likewise didn't have any fuel restricter -- the fill-up passage was wide open, so I think that it's perhaps normal for the '75 model year?

It wasn't a CA car, however.

My 240 does not have the fuel restrictor either, it's an open tube right to the tank, but I have never had a problem with filling up. Is it possible that there is some thing in the tube that is causing the fuel to back up and stop the pump? If you are filling up slowly and and that seem's to work, try poking around the filler tube with a coat hanger just to see if it is obstructed

If you're going to "poke around" don't use metal that sparks. Metal coat hangers are probably not a good idea in a gasoline fume environment.
--
1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.

LOL... that's all I have to say :)

I totally agree with Trev29. Find a piece of wood dowling or something similar. Be Careful.