My tanks were 90 percent full, valves were open on all wing tanks, the fuel warning light came on, I notice a NO FLOW of fuel in the fuel filters, there are no restrictions in the fuel lines, I was near a runway and landed, after landing the fuel flowed again. Happens several times and I now only fly close to landing areas. Have tried one side then the other, also with and without fuel filters, tried joining the left and right wing tank fuel lines together, tried one inlet to the collector tank and used the other for a vent above the wing. Have run out of things to try and the problem still exists. ANY SUGGESTIONS?