Mom's 87 Ciera having fuel issues

[Bonneville92V688]

So mom's car is having some problems. When you start it up after letting it sit, it shows signs of being flooded (backfire through the intake/exhaust, inside of air cleaner is soaked with gas, very hard to start). The only way we can get it to start is if we pull the fuel pump fuse and crank it until it tries to start and then we put the fuse back in and it fires up. I also notice that after you turn the car off, the fuel pump runs for about 5 seconds and then goes off. Are these all signs of a failing fuel pump relay? Or is this the bad oil pressure switch thing that GM TBI motors experience? She doesn't want to go willy nilly replacing random parts because she can't afford it at the moment. Any help would be great as she needs her car daily.

BTW, it's an '87 Ciera with the 2.5 Duke.

[Jrs3800]

Could be a problem with a sticking relay, but the flooding is telling me that either the injector is bad or possibly the ECM.. The real question should be why is the injector injecting so much fuel.. When you turn the ignition on it should spray really quick and stop, then when you turn it over you should see it pulse... Sounds like the injector has failed open or the ECM could be fried...

Just some possibilities for you..

[95se]

X2 on a sticking injector or the ecm, ive heard ecms are common on them, find the ecm and do a knock test on it