car runs and turns off after a while.

[Fbomb19]

Car is nothing but problems but this one is the main one. The car drives good and what not but when i drive like 50-70 miles or some where far, or if i use the car alot It just gives out at some point. Its happen b4 and today it did again, like i said it happens when it goes for a long ride. The temperature doesnt read hot. Ill be driving like 5th gear on the way home from a long ride, and then the car just starts to die down. ill notice it loses power and its about to stall it self while im moving. I try to give it gas but, that does nothing. The rpms just fall and shuts off. If i try and turn it back on it takes a little while to turn on, and when it starts it might run for another 5 min, and shut off again. If i let it sit for like a hour it might go a little longer but shut off in like 15min. If i let it sit over night then its good for another 50-70 miles. When it shuts down the ignition is still on.... just the motor dies out. I was told that its my fuel pump giving out. How ever i dont want to replace my fuel pump and then it turns out to be somthing else. the car is a 89 240sx single cam btw. Also when i floor it somtimes it may smell like gas inside the car. ANY help will be great. ! save me some time and stess.