I told the production engineer at Kohler today that the information in their operators manual about cranking the 28 efi on the Hustler Super Z did not work. He said that Exmark had the same problem with duel tanks, and if it was a single tank setup it worked fine. He said the setup with duel tanks cause the gas to vapor lock but I was the first one that had mentioned it on a Hustler and the pump would not move the gas up unless the return was installed so it could breathe. The Schrader valve he said was installed on the fuel line so you could place a gage on it to test the pressure and to release the pressure so you can work on the fuel system. I told him I let the fuel run out of one tank late yesterday and used the procedure that was outlined in the operators manual for three different attempts and it would not start so I took a cap off of a lubricant can and took a small Phillips screwdriver and caught the gas that I bled out and it cranked right up. He said you are not suppose to bleed the schrader valve because it can be very dangerous with gas coming out around the hot engine and he needed to talk with Hustler about that before someone was burned.