1997 Oldsmobile Delta 88 turns over but won't start

Hi
Well it all started when I took car to garage to get fuel line fixed, it was leaking by tank. They dropped the tank, rebuilt sending unit and replaced the metal part of the lines from tank which then connect to the main fuel feed and return lines. Now when I try to start the car it just turns over and after long time will start, if I turn the key on so dash illuminates then back to off position then on again then continue with key to turn over engine it will eventually start. When they rebuilt the sending unit and I first got car back the fuel guage did not register past empty, I took it back and they dropped tank again and I was told the sending unit was installed improperly, guage then worked but now I have this other problem with starting and garage guy said stuff like this happens and I refuse to pay him more money.
please help
Lynn