If it runs OK when the tank is full, then the pump is probably not the problem. Maybe fuel pickup fell apart. Maybe too much of the wrong kind of pressure in the tank. Check your gas cap gasket. Maybe your fuel gauge is inaccurate. Hesitation on acceleration could be any of a number of things, but if you take that in the context of the 1/4 full argument, then I'd start looking at the tank and it's innards. At least that's what I'd try first. Simple, then complex, then impossible, then sell the car...
1987 BMW 325
[This message has been edited by jeffsr (edited 04-19-2000).]