Where are the NIH gasoline, ethanol and diesel pumps?
They are located by the NIH Fleet Management Branch in Building 12.
This map shows the location: 
What about refueling natural gas vehicles?
The NIH Fleet Management Branch has many vehicles that run on natural gas. Refueling of these vehicles is remarkably similar to filling a car's gasoline tank. Visit the U.S. Department of Energy's Refueling Station Address Locator to learn where to refuel the natural gas vehicles.