I installed one of the new Carter carbs. Just putting around at low rpms and zipping around the farm everything runs better than ever. But After running down the road for a while - 5-10 minutes or more - at higher engine speeds, it runs out of fuel. I have a clear in- line fuel filter right before the carb and I can see there’s no fuel. If I disconnect the fuel line at the carb and immediately reconnect it, fuel rushes in, it starts right up and I can go down the road another 5 minutes. It’s almost like a vapor lock that prevents fuel delivery. Any suggestions?
Originally thought that may be the problem but it’s not. Makes no difference.
I added "quotes" as posts were hidden. I agree with Percy that it may involve the pump - or somewhere else in the delivery. Do you have a glass bowl pump where you can see the level? How's the tank (debris)?
To me, your last sentence was the most important. You disconnect the line at the carb. You don't indicate the back pressure (tank, pump, fuel delivery line) pushing fuel out - indicating a carb block or stuck needle. Upon re-connection, you get immediate flow (not an expert on vapor lock-but it seems that's resolved with removing the heat source, i.e. repositioning the fuel line).
Have you tried swapping out the filter (even though it shows empty)? What it sounds like you're describing is fuel delivery at low demand but starving at higher demand. The pump should keep the carb full.
There could be some trash in the line that higher rpms/vibrations are affecting flow. Any maintenance on the fuel lines themselves? Have you disconnected and blown lines clean?