I recently had problems with two different Zama carbs running Gas/Glow. The diaphragms are apparently not resistant to the fuel mix, and will swell up. I believe I have run every different type of diaphragm material they make in the Walbro carbs with no problems on Gas/Glow, but watch out for these problems with the Zamas. Keith at BME told me that he had run Zama carbs on glow fuel in the past without problems, but perhaps they have changed the material in their diaphragms.

It was a bit strange when I had the problems. The first day, the engine ran perfect, and when done I ran it dry like I always do and injected after run oil. The next day, it was like all of a sudden the carb was all out of adjustment, and then, while trying to adjust it, it finally got to where it just wouldn't richen enough. After some trouble shooting I found the swelled diaphragm. I tried another Zama carb with a new diaphragm, and the same thing happened. Could be a bear to trouble shoot for someone not really familiar and comfortable with carb work....

AV8TOR