Taylorcraft pilot reported making an emergency landing due to engine malfunction. Reporter stated he initially thought it was a fuel problem as the wing tanks were not draining into the main; but that there was adequate fuel in the aircraft.

Narrative

Fuel from my wing tank was not draining into (filling up) my main tank. Therefore I diverted to the nearest airport; using my Lowrance 2000C; that airport was a military airport. However I received no response from the military Tower. Upon reaching the field I noticed it was deserted; no planes; people; or fuel pumps were visible. So I then turned south to the next closest airport. I was cleared to land at the second airport; when my engine sputtered. Fearing fuel starvation; I examined my options; continue to the second airport and possibly not make it; land in a small field to my right; or land on the asphalt at the military airport. I elected the closest and safest option; land on the runway at the military airport. Speaking with the second airport's Tower I explained my situation and declared an emergency. Upon landing at the military airport my engine continued to run as I taxied around for a suitable place to park. (Next to the Tower) I dip-sticked my main tank and found 2 gallons were still in there. I arranged for fuel to be brought to me. The linemen brought me 10 gallons. The 10 gallons would not fit in my main; 12 gallon tank. That verified that I had more than 2 gallons remaining in the main tank when I landed. The linemen can verify that the fuel overflowed from the main as I tried to pour in all 10 gallons. I put the remainder of fuel in my right wing tank. So; although I thought I was running out of fuel; I did actually have enough fuel in the main tank for a legal VFR reserve. (My Continental 65-8 burns 4 gallons per hour; so 2 gallons equals 1/2 hour of flight. Also; all fuel in the main tank is useable as it drains from the bottom center.) Plus; I also had some fuel in the wing tanks. (Although it apparently wasn't draining into the main as it should.) I absolutely had enough fuel on board for a legal VFR reserve. Given the situation; I erred on the safe side and landed before I ran out. I have recently purchased new vented fuel caps for the wing tanks as they are believed to be the reason for the fuel not draining into the main.