[AT] A Few Questions

[Mike Sloane]

It has been my experience that having to run with the choke can be cause 
by fuel starvation OR a vacuum leak in the plumbing between the 
carburetor and the manifold - loose fasteners either at the carburetor 
or manifold, warped carburetor top, bad/missing gaskets, or pinholes in 
the intake manifold casting.

If indeed the problem is a vacuum leak, then one of the easiest ways to 
locate it (after tightening all of the nuts and bolts, of course), is to 
slowly move the head of an UNLIT propane torch, with the valve just 
cracked open, around the intake area with the engine running. When the 
raw propane is sucked into the combustion chamber through the leak, the 
engine will pick up speed. The reason for moving slowly is that it takes 
a second or so for the propane to get up to the combustion chambers - if 
you move too fast, you will be past the leak before the engine speeds 
up. It also helps to do this in a sheltered spot - where the wind won't 
blow the propane away.

Mike

On 7/5/2011 10:49 AM, charlie hill wrote:
> Doug, I agree completely about fuel starvation.  It's been my experience
> with Zenith and M&S carbs that fuel starvation is usually due to trash or
> water in the main jet but it could also be obstruction in the fuel tank or
> line.
> It would be wise to check all of the above.
>
> Charlie
>