muzician21 wrote:

I got a new diaphragm, but looking at the old diaphragm, it looks to
be intact and in good shape. The material still seems pliable, I held
it up to a light and can't find any breaks in it, including where the
choke plate rod is attached.


The diaphragm was always good. You never had any symptoms that indicated a bad
diaphragm.

When you fill the tank all the way to the top the diaphragm isn't even needed
because on this style carb it is only really needed when the fuel starts to drop
below full.

Your problem is the choke is not closing. There is a spring that closes the
choke. The spring may be broken or missing. The diaphragm pulls the choke open
once the engine is running. If you had holes in the diaphragm your symptoms
would be the opposite - you would be getting too much gas as it would be sucking
gas in thru the holes.


The longer of the two pickup tubes had a fair amount of crud on the
screen, which I've cleaned off. Gonna put it back together with the
old diaphragm and see if it starts any easier with that pickup cleaned
off. If it does, I'll store the new diaphragm in the refrigerator for
future use.

And why are there two pickup tubes and why are they different lengths?


One tube (the longer) goes down to the bottom of the tank the other goes in a
small reservoir. Part of the diaphragm is the fuel pump that pumps gas up into
this reservoir (there are two flaps that act as pump valves). the gas in the
reservoir stays at a constant level because what ever extra is pumped in just
overflows and runs back into the tank. When the tank is full then the reservoir
is also full so no pumping is needed until the fuel level drops down.
The small tube feeds the main jet which controls the air fuel mixture. That
mixture is adjustable with the threaded needle valve.

-jim