Error Code

I have an error code of p1237 which is Fuel Pump Secondary circuit fault. So, I know it involves a nice, expensive, hard to reach item, but what exactly does it mean? And would it cause lower gas mileage?

I have an error code of p1237 which is Fuel Pump Secondary circuit fault. So, I know it involves a nice, expensive, hard to reach item, but what exactly does it mean? And would it cause lower gas mileage?
Take a look at the fuel pressure regulator, see if it's pluged in and see if the vacuum is plugged in or if there is gas inside the vacuum when the engine is first started. that code has to do with the regulator.

Ok, that stretches my knowlege of the car. I know only what i learned in first year auto-tech class, which is a hell of alot more than 90% of the people out there, but you may have to go into a little more detail. Well actually just tell where that stuff is so i can check it.

I also have to say something i didnt say in my orginal post. I've only been getting about 10-13mpg out of my taurus. The first two tanks i filled, i put E85 in it and i was getting 14mpg which is about right for my Taurus. But with the price of E85 being almost more than gas, I've been filling it with gasoline. My mom was interested in using ethanol in her FFV van so she asked the Chrysler dealership she bought it from, and they said that the ethanol can act like a cleaner and dislodge sediment and residue in the fuel tank/fuel lines. Would this have anything to do with what im seeing?