This has been a rough week in regards to the rebuilt(or cleaned up) Weber. I have installed it, and uninstalled it, and reinstalled it about 30 times in the past week and have had nothing but trouble. As I installed it the first time, I couldn’t get it to even start properly. Very sporadic results. After troubleshooting, removing and reinstalling, multiple times, I tried reinstalling the old float needle, readjusted the float, just everything I could possibly think of.
I finally thought of something in the middle of the night. The PO had installed gasket sealant along with the thicker than average gasket between the manifold and the carb. Why? Because I took the carb off and found that the bottom of the carb was warped. So, I had some 180 DA sandpaper and attached it to a piece of straight sheetmetal and set the base of the carb on it and started to slide it back and forth to attempt to remove some of the warpage. After about 10 minutes, I could see all of the low places on the carb were now gone. Then reinstalled the carb and the bus actually started very consistently and still does. The warpage was causing a vacuum leak.
Now, the only problem is that it WILL NOT idle. I must continue giving it gas to keep it running. I have removed the idle screw, recleaned it, and blown compressed air with no change in idle. Also, removed the jets and cleaned and blown out also. Still nothing. I am out of ideas.