hi there, i bought a geo metro 91, last week and there are a couple of questions that I have, is there a light on the dash that flashes when the fuel tank is using the reserve of gas?
and the other question that I have is:
Where is located the screw to regulate the minimum of the car?, i think that is expending more gasoline than usual because the minimum needs to be adjusted

I think that you mean the idle. There is an idle screw hidding under a black rubber plug on the right side of the throttle body (as you face the motor, drivers side for most of us). You can turn it in to reduce the idle. If you are getting bad gas mileage, look into a new o2 sensor. I do not think the Metros ever had a low fuel light. I could be wrong but I have owned 2 92's 2 93's a 94 a 95 and a 97 and none of them had one. I hope this helps.

also make sure air cleaner is good. if its dirty will really make mileage drop

thanks for the tip, i will try to setup the idle, i'll let you know what happens

My 91 metro doesn't have such a light for the gas. I believe the reserve is 2 gallons. So if you get 45+ mpg(like me), that's close to 100 miles you can travel in the red - LOL!