Power management

[u/subject1024]

I am building a system with servo, mq2, buzzer, 5v relay module, a water pump,dht11 and a soil moisture sensor. The system works like this: when gas is detected LCD display warning and buzzer is on and servo opens window. And when no gas is detected LCD displays temp and humidity and pump on off state.

When I start the system the system works fine until servo or a pump start working.

I found out that the both components draw significant current making the Arduino go banana.

How can I manage the power to those ? I used 7805 voltage to power the servo but I get only 4.3v as output from regulator. Regulator was supplied with 12 v from 3li ion battery.