As the question refers, I have this 1997/98 nissan almera wit a/c . Its a 1.6 Ltr and i believ it should consume less fuel than my golf 3   1.8ltr.

The thermostat of the ALMERA was removed when it came into the country( i was very angry )  I just noticed that it kinda consumes more fuel than normal
So does the thermostat affect fuel consumption ?

Yes it does, removal of the thermostat allows your car to run longer in an open-loop (more fuel consumption) situation especially when you start your car from rest before a signal is sent to the ECU that the operating temperature of the coolant has been attained which is attained much quicker when the thermostat is in place. Since your thermostat has been removed, your cooling fans have also probably been by-passed which makes the fans kick in immediately you turn your ignition on, hence, attaining the manufacturer specific operating temperature takes a longer time before the fuel system starts operating in a closed-loop situation (normal fuel consumption).
You can replace the thermostat by getting one from Ladipo market or your spare parts dealer. It costs about 2,000 naira only, and if your fan has been by-passed to run immediately when the ignition comes on, try and get an experienced auto-electrician to revert the system back the way it was before the change and that problem should be solved once and for all if your cooling system has no other problem associated with it.
Kindly try and observe the parameters on the dashboard especially your temperature guage after you re-install the thermostat.
The professionals in the house like[b] Siena[/b] would be able to help you out much better than I can especially with signs (soot) on your spark-plugs and inlet manifold to confirm that you are having an abnormal rate of fuel consumption.

That someofab@@@*   Mechanic is goin to cost me 2k now if not more? Thanks for the insight. I was really wondering how my small "blender" of an engine would  be guzzling fuel like an elephant!!!?

My temperature guage hardly reaches the mid point most times even on hot afternoons, I gues that means the car never reaches the correct operating temperature!!

You are absolutely right.

my golf 3 thermometer on d dashboard gets to d midpoint 10mins after d car is started and remains there as long as d vehicle is on.even if d engine is extremely hot and frying,it remains there.am 100% sure my engine is over heatin.what do i do plz??.oga siena and freiends in d house

Your engine isn't frying. The mid point is the correct position your temp gauge should reach to attain optimum working condition. The fact that your engine feels like a bakery is irrelevant. As long as your gauge is working normally, you have nothing to fear.

ok my boss.hw do u explain d boilin radiator water wen i open d engine.2ndly i think d heat is evn boiling the fuel directly and evaporatin it.makin my vehicle to consume for fuel than usual