The Chevrolet Beat model is capable of providing the fuel economy in the range of 14 to 18 kmpl. Where in heavy traffic conditions of cities its mileage can reach up to 14 kmpl, on long highway journeys it is capable of providing mileage of up to 18 kmpl. However, the mileage can differ from person to person, depending on their driving behavior.
Please check following things
1. Is Fuel pump noisy. If yes change the fuel pump motor. Its cheaper than replacing whole fuel pump.
Swift Diesel Fuel pump motor is compatible
2. Check Battery voltage at Glow plug point it should be minimum 10.5V. If not change battery
3. Last option is check fuel injector leakage and get it callibrated
It is advisable to start a car once in a week or two and take it for a spin if possible, so the battery get recharged. Also, if you are planning to park it for a longer period, we will advise you to get jack stands and also to disconnect battery terminals, then you won't need to start it again and again.
What we can understand from your question is that, your tachometer is not coming up and the car is not starting. It could be because of a dead battery, we will recommend you to jump start your car if you don't have jumper cables and a good battery, you should it take it to the nearest service center. Other problem can be related to the start relay or electricals of the car.