HELP! Fuel problems

[chick]

I had to pull the fuel tank off my 89 coupe, to repair a dent under the sender unit. All done, no leak in the tank (pressure tested with air), put it back in, all seemed OK. Now there's a large smell of fuel from somewhere, can't find it. When I pop the filler cap, there is a loud WHOOSH, can't tell if pressure or vacuum. And after a few minutes, the car stutters and the engine dies. I don't think the lines are hooked up wrong, but....?
Any ideas?

[jlevie]

My first thought, based on the fuel smell is that the vent line might not be hooked up, or the fill hose not correctly attached. But either of those would mean that the tank could only be at atmospheric pressure. When operating normally, the evaporative control system will hold the tank slightly below atmospheric pressure to prevent gas vapors from being vented to the atmosphere.

Excess vacuum in the tank, from a pinched vent hose, could explain the whoosh and might possibly explain the engine dying after a few minutes. One way to see if that is the case would be to leave the filler cap loose and see if the engine will run normally.

I don't know how you'd manage to get excess pressure in the tank unless the vent system is plugged, the evap control valve is inop, and the fuel tank is heating up enough to self pressurize. That could cause a leak at any of the connections or at the level sensor/pump seal.

If the fuel smell is strongest in the cabin when the heat/AC is off and set to recirculate, then I'd suspect the leak to be on or around the top of the tank. If stronger with heat/AC on and not set to recirculate the leak could be in the engine bay.

In any of those cases, I suspect that the tank is going to have to come back out. And when re-installing make sure that all of the lines are clear of pinch spots.