Should the fuel tank be pressurized? Options

[RoadGlue]

My tank has been building up a large amount of pressure. Is this normal on a stock '74 2.0 w/ Djet? After a hundred miles of driving, if I remove the fuel cap it lets out a lot of air. I may be tripping, but I just don't recall this happening with my other Djet car.

We're about 600 miles from home and I've been having off and on problems with vapor lock on this trip. Hard starts have been a real issue, but I've found that releasing the pressure in the tank seems to help remedy the situation.

Thoughts?

[Cap'n Krusty]

Pressure is NOT normal. As it's vented through the vapor recovery tank, simply pulling off the 3.5mm hose from the overflow tank to the vapor can should take care of the problem. You could also remove the line from the filler neck to the overflow tank and check that the little tubes (or the line itself) aren't blocked. If you run with those hoses off, be prepared for a fuel odor in the cockpit. The Cap'n

[RoadGlue]

Thanks John!

I had the same thought and pulled off the line on the overflow tank just a 1/2 hour ago. Yeah, getting some vapor smell. I'll see if I can't find where the clog is before we head north.

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[ClayPerrine]

It's probably vacuum, not pressure. If the charcoal canister system is somehow blocked, the tank will end up in a vacuum, and that can cause what feels like vapor lock, but what is actually happening is that the pump can't suck hard enough to overcome the vacuum in the tank.


Next time you get "vapor lock" pull the gas cap off. If I am right, the car will start back up quickly.

And like the Capt'n said, you need the charcoal canister system there to prevent gas smell in the car.