1993 Ford Taurus Engine turns over but won't start

Mom has a 1993 Ford Taurus. About 5 months ago she was at a store, when she came out to leave, the car wouldn't start. It would turn over, plenty of power, but would not fire. Had it towed to a mechanic. He replaced the fuel pump. Worked fine for a day but the same problem came back. Replaced the fuel pump again. This time it worked fine for five months. Now she has the same problem with the car not starting but it will happen occasionally. Took it to the mechanic. He couldn't get it to "not start". Made no repairs. I went to her house and tried to start it and it started easily. Then I started it and turned it off, started it and turned it off about six times. Then the problem came back. The car would turn over but wouldn't start. Strong smell of gas present. Do fuel injectors "flood"? Would this be another fuel pump problem or something else? Thank You.