Experiencing a true "vapor lock" where the fuel in the lines boils and becomes a vapor is about as likely as finding a chicken with lips. I've seen it maybe a dozen times in the past 60 years. It's much more likely that you've got a restriction in a line, an air leak on the inlet side of the fuel pump, a bad pump, or some kind of debris in the fuel tank that's blocking the tank outlet periodically. Putting a filter anywhere on the suction side of the pump is probably the worst possble choice- - -it promotes air leaks, and suction on the gas from pulling it through the filter will actually make a vapor lock more likely. The best place to put a filter is at the carburetor inlet, working with pressurized fuel. Do the 3-part test of the fuel pump that I've suggested for years- - - -volume, pressure, and vacuum. If you do that, you'll be one of maybe 5 or 6 stoveboilters who have taken my advice on fuel pump testing in the past nearly 20 years.
Jerry
