Thanks for the information. Yesterday I removed the engine from the airplane and mounted it on a test stand. It had the same problem as it didon the airplane. ( would not hold suction )
I removed the fuel line from the carb and blew back into the tank with the vent line still connected to the pressure tap on the muffler. The tank pressured up and there was no flow out the vent. The pressure tap on the muffler was plugged solid. I took a small drill bit and cleaned it out..... problem solved. Since this was a 25 year old "new" engine, I was surprised. I believe an insect had built something into this hole. I recenly had the same problem with a nail gun. A small waspbuilt a mud nest in the opening of the air intake. They also get into my tool boxes and build mud nests into tools etc.. The pressure tap on the Super Tigre may have been a spider's home. Anyway, thanks again to everyone who responded with ideas.

A.D.