1986 carbureted Toyota Corolla start problem

I have a 1986 Corolla (FWD, 4AC engine) with 50K highway miles (all
mine) that over the past few months has gradually become harder and
harder to start, hot or cold. It always cranks fine but either dies
right away or chugs and gradually increase in RPM.

I've checked for vacuum leaks and gone through the factory manual's
procedure for checking the emissions and fuel systems, except for the
tests requiring high altitude or temperature below 45F. I also checked
the carb adjustments (choke opening, base and other idle speed). The
AAC diaphram doesn't leak. The fuel solonoids click when voltage is
applied directly to them. The choke mechanism doesn't bind, and the
choke seems to open gradually as the choke spring uncoils.
Acceleration is fine, hot or cold, at least as well as can be expected
from 75 HP.

A year ago I changed the plugs (NGK), vacuum hoses (all Toyota), and
had the engine checked (175 PSI, 5% leakdown). Oil consumption is
better than a quart per 5K.

What could be the problem?

"Snookums" > wrote in message
oups.com...
>I have a 1986 Corolla (FWD, 4AC engine) with 50K highway miles (all
> mine) that over the past few months has gradually become harder and
> harder to start, hot or cold. It always cranks fine but either dies
> right away or chugs and gradually increase in RPM.
>
> I've checked for vacuum leaks and gone through the factory manual's
> procedure for checking the emissions and fuel systems, except for the
> tests requiring high altitude or temperature below 45F. I also checked
> the carb adjustments (choke opening, base and other idle speed). The
> AAC diaphram doesn't leak. The fuel solonoids click when voltage is
> applied directly to them. The choke mechanism doesn't bind, and the
> choke seems to open gradually as the choke spring uncoils.
> Acceleration is fine, hot or cold, at least as well as can be expected
> from 75 HP.

Start with the basics - air, fuel, and spark at the appropriate times and
quantities.

You mentioned choke opening, but how about closing? Does it close when you
depress the throttle pedal to the floor and release it? Of course, this
wouldn't affect hot startup.

On the hard start when it is hot, will it re-start immediately after you
shut it down or do you have to wait for a few minutes?

What is the fuel level in the bowl when it is hard to start? There should
be a sight glass on the carb with some bumps on the side of the housing that
holds the glass. The fuel level should be even with those bumps, about
halfway up the glass. If the fuel level is low, the float might be sinking
or the fuel is draining out somehow.

Are you getting spark when cranking?

>
> A year ago I changed the plugs (NGK), vacuum hoses (all Toyota), and
> had the engine checked (175 PSI, 5% leakdown). Oil consumption is
> better than a quart per 5K.
>
> What could be the problem?
>
--
Ray O
correct the return address punctuation to reply

"Snookums" ) writes:
> I have a 1986 Corolla (FWD, 4AC engine) with 50K highway miles (all
> mine) that over the past few months has gradually become harder and
> harder to start, hot or cold. It always cranks fine but either dies
> right away or chugs and gradually increase in RPM.

As my 89 Festiva has aged I have to pump the accellerator to fill the
float bowl or something, especially if has sat for a few days. Startup
idle can be erratic but it restarts fine after being shut down.

Have you tried spraying carb cleaner into the throttle body when warmed up
at idle to clean out the interior?

--
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My 1990 copy of the Lemon Aid used car buyer's guide points to a
defective Ignition Control Module (transisterized points module inside the
distributor) in 1985-86 Corollas which can cause stalling or hard
starting. Toyota was replacing them free of charge under a recall program.
You can get ICM's tested for free at some parts stores. I've had to replace
the ICM on my Festiva twice. I wrote something about it for my website
(see below) under "Cars". I recommend the heat transfer grease used in
computers when installing a replacement.

It also says older cars with stalling problems should have the valves
checked for carbon buildup. Maybe the valve cover can be removed and the
valves sprayed with solvent to clean them? I used the stuff you put in the
crankcase just before changing oil to clean the valves on my Festiva but
was advised here that could intro nasty hard bits into the engine. If your
compression is uniform I'd guess against uneven carbon buildup on the
valves.

--
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William R Watt National Capital FreeNet Ottawa's free community network
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check the ignition coil, especially if yours is inside the distributor
cap