Pressure cookers, especially the modern ones - require a bit of trial and error. For me, I have to force myself not to add too much water when using it. Too much water makes the final product taste bland. 1 cup or 1.5 of water is really all you need. Just monitor it so nothing burns.
Here's my cheat sheet for the cooking times with a pressure cooker. I find this very useful. http://fastcooking.ca/pressure...
I'm not sure what type of rice you use, but rice can be very tricky with a pressure cooker. I eat a lot of rice - my favorite is jasmine rice - and I find it so easy and straightforward to just make it on the stove - no tricks or special equipment like a rice cooker. When I make rice, I use the ration 1 cup of rice to 1.25 cups water. I rinse the rice a few times to get the water clear, pour the water based on the amount of rice being cooked, and bring to a boil. You have to keep an eye on this - 2-3 minutes! Once it comes to a boil, lower the heat to barely simmering - LOW setting. Stir the rice for about 20 seconds to incorporate the water. Don't worry if a lot of water is at the top. Cover with a lid and let cook on LOW for about 12 minutes. At the end, take it off the heat and fluff. Wait 5 minutes and enjoy.
Like I said, this is how I make jasmine rice. With other types of rice(brown, arborio, etc), you will need to tweak the method.
FYI: Avoid supermarket rice - Uncle Ben's, Riceland, etc. It's just tasteless, mushy, crappy and overpriced. Check out Asian or African markets for rice.
Jasmine rice is truly the best - so flavorful that I sometimes add a little olive oil to it, salt and pepper and eat.