I think I was ripped off from a local dealership?

I have a 2008 Ford expedition. Last weekend it would turn over but not start. We had the fuel pump replaced. Today, the same thing happened. I checked the voltage on my battery this time, and it was at 10VDC. When I jumped my car, it works fine. Could the 200 dollars to replace my battery, have saved me 1200 for the dealership from replacing my fuel pump? Wouldn't the computer system tell them this?

Probably not.

If the car was cranking over normally and not starting, then the batter was OK at that time. So chances are it wasn't getting any fuel, hence the new pump.

If the battery voltage is down, you wither have a bad battery, or the alternator isn't working properly. But if the car runs OK after a jump start, then chances are the alternator is working, just the battery isn't holding charge.

Check your alternator

No they most likely fixed your car.

You can ask for the bad pump that they replaced and connect it directly to the battery. If it works, you got hosed.