"Ted" wrote in message ...
Can anyone kindly explain the choke operation on a 1998 Merc 90ELPTO? I
just bought a used boat with this motor and I would like to know the
"correct" way to start the motor with the choke, and how the choke
works. What I was told by the salesman was the ignition key can be
pressed in to "engage the choke". Does pressing in the key BEFORE
cranking the motor "preengage" the choke? Does pressing the key in
squirt gas in the carbs each time it is pushed in? Or does pushing the
key in just enrich the mixture while it is pushed in? Should you press
the key in once and then crank? Or do you have to hold the key in while
cranking, and then maybe a little after it starts? What about the "fast
idle" lever? What is the best way to work that into the procedure?

I think I would have better luck starting the motor if I actually knew
what was going on with the choke!

Thanks in advance...

Ok, let's square you away on how a choke works, and to do that we need to do
Carb 101. A carb is a venturi, when you flow air through a venturi it
creates a low pressure area just downstream from the expanse in the neck.
This low pressure is what pulls the fuel from the bowl through the metering
jet and into the engine. The "choke" is a plate at the opening of the
venturi which when engaged, restricts the airflow, thereby further reducing
the absolute pressure in the venturi causing the fuel to come through the
jet at a higher rate. So you see, the engine has to be turning for the choke
to have any effect whatsoever. On these motors, the choke is activated by an
electric solenoid which is what you hear go "click" on the motor when you
push the key in. It releases when you release the key, therefore you have to
hold the key in while you are cranking in order for the choke to have any
effect.
Chokes do not "squirt" gas into engines, however, some carburetors are
equipped with accelerator pumps which "squirt" a metered amount of fuel into
the engine as you advance the throttle.

Hope this helped unconfuse you.