Toyota Repair: hard start when cold, variable venturi, teflon coating

Question
thanks for the ans ted but im still confused about why its harder to start when its cold out rather than warm. what is the carb doing different in cool weather as opposed to cold weather.and why does advancing the timing make it start immediately? THANKS
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-----Question-----
i have a 1988 tercel auto with 1.5 1 barrel carb. car has 60.000 origanal miles and im 2nd owner. car is mint condition and fully tuned. my question is when the temp goes below 35 degress and sits over night it is hard to start in the morning. any other tempurature and i just depress the pedal once and it starts right up the choke goes on and operates just fine. even when i do get it started when it is cold out the choke does operate then also. one little thing that might matter is when the car is hard to start when left overnight in 35 or less temp all i have to do is advance the distibuter by hand just a little bit and it starts immediatly then i just put the timming back to where it should and im good to go. so far nobody can tell me why this happens. any thoughts?
-----Answer-----
Ronald,

I hate to tell you this but you probably have a bad carburetor. The Tercel does not have a choke, it uses a variable Venturi carburetor with a Teflon coating on the piston.  When the Teflon gets scratched or cleaned with carb cleaner it is pretty much done for and sticks badly in the bore causing the engine to run lean. When I worked at Toyota a few years ago that carb was $800 bucks. By now it might not even be available.  I would try leaving the timing advanced and see if it pings when hot. Otherwise seek out a good after market carb such as a webber.

Answer
Ronald,

When an engine is cold it requires more fuel to get it running. The reason is that the cold metal causes fuel to puddle and stick to the intake manifold and cylinder walls. Therefore a richer mixture is used to supply enough to burn in the cylinder and to accommodate the cold metal. When you change the ignition timing it allows the engine to run on a bit leaner mixture allowing it to start. Now understand that with fuel injection this is not a problem since the fuel is sprayed as almost a vapor and is directed strait at the intake valve.