Good day people.

I have this honda civic lxi model. And this is the scenario. At first the car have this overheat problems during long trips w/c leaves no water at the radiator. We removed the thermostat and have engine tuned up and no leaks were found in the radiator however we observed that when the car revs high, the water in the radiator pumps its water out to the reservoir little by little. After a week, the car would no longer start. It was found out that the valves were worn out so we change the valves and so the car finally went ok. Tune up was done and change oil too. Only to find out that it was already consuming too much fuel. From 12-13 km/liter, now 7-8 km/liter.. The car feels great naman. Tune up adjustment is 10-12 kasi noong 9-11 sya na mejo tumataas engine temp. Anong normal setting pala para makatipid?

My inquiry po:

What must have cause the poor fuel consumption?