If you have trouble getting a GPS fix on your Epic 4g Touch. I am going to give you a few tips I find that gets the signal to lock faster. From my trouble shooting it seems like you can not have the phone in your hand. If you place the phone on a flat surface and do not move it chances are better it will get a gps fix. If the phone takes too long in one spot try moving it a few feet to the left or the right. I find that every time I pick the phone up the GPS signal drops drastically. Even though I can get it to lock the accuracy is never within 50 feet its usually 200 or so feet. You can also try using an app from the market called GPS test. GPS test will allow you to see how many satellites the phone sees, and how strong the connection is between the phone and the satellites. Hope this info helps anyone who is having problems with their GPS.
For those that do not know; location can be found via 3g, 4g or wifi but gps is accurate down to street level. Location is a relative position this is why Google maps can tell you your area without the GPS being on, but for voice navigation to work there must be a GPS signal.
Reflashing to another version is a placebo. GPS is unreliable no matter what. It might work perfectly for a couple of weeks and lead you to think you've found a solution. It will be broken again soon. No software revision, no Samsung repair, and no Sprint repair will do the trick. I've tried them all. Try running a GPS tracking app and hiking into a hill. It will permanently lose lock as soon as you lose your cell signal.
The SIII is a great computer, has a quick-locking GPS, and runs Android 4.1.2 (and higher ifyou want to bother). It doesn't drop calls, and the battery life is fine for me . The only difficulty in my case is that it is a 4G LTE modem, and there is no 4G LTE in my area, and no prospects either (Washington DC). Apparently Sprint thinks it is a higher priority to bring 4G LTE to Longview and kerrville Texas and Shelby North Carolina (no offense intended, small towns) where they have 35 customers, and not to large cities where they have tens of thousands. They are giving them away for free when you renew. At least from what I read, the S IV isn't really that much better. The Epic 4g Touch almost made me leave Sprint, too. They pushed that phone hard, knowing it was buggy and basically a useless brick. Their behavior was indefensible, unethical, and moronic. Now I'm glad I sold it and moved on. Your mileage may vary. Good luck.