ralfyguy wrote on 07/29/10 at 08:34:58:Drunken Dwarf can you try something for me?
With the engine warmed up and idling, squeeze the vacuum hose off with your fingers on the u-bend and tell me if the idle seems to rise a bit, and when you let go seems to go back down.
I performed this test again with the petcock in the ON and RES position and got the same results.
I then setup the petcock up as describe in the thread
Test your Petcock.
The engine idled at faster rate then usual. Very similar to having the vacuum line pinched.
With the test setup I bottomed out the idle mixture screw without the engine stalling.
So this points to either a leaky vacuum hose or petcock diaphragm. Does anyone have a suggestion (or bet) on which one it is?
After the engine cools I'll install a new vacuum hose (got some 3/16 inside, 3/8 outside diameter fuel hose from Lowe's) and try again.
-D. Dwarf