I have a 1981 Toyota Corolla KE70 "DX", 4K engine,
Malaysian market.

The original Aisan carburettor was 21100-13370.

The carburettor on my car had no emission control
outlet, valves or diaphragms.

I purchased a brand new carburettor from one of
the local dealers recently, but after a few months only,
it has started giving trouble - the vacuum outlet to
the distributor advance diaphragm now has vacuum at
idle when there should be none. Further advancing the
throttle hardly gives any increased vacuum suction,
thus there is hardly any resultant advance in timing.
The car accelerates very sluggishly as a result.

The trouble definitely does not lie with the diaphragm
at the distributor, but the carburettor's vacuum outlet.

The mechanic can't seem to figure out what's wrong.


(This post was edited by Tham on Jun 27, 2005, 9:24 AM)

If this carb ran well for a couple months and suddenly changed it may be defective. Many will run better with vacuum disconnected at distributer and plugged off, with your complaint. Is there any chance hoses were mixed up?.....since it was running well? Good luck,
_________________________________________


Tom Greenleaf - MetroWest, Boston
http://acsource.net/acforum/index.php

Thank you, Tom.

I had never thought of disconnecting and plugging
off the vacuum hose. I'll try that and see how it goes.
Performance will be retarded further, no doubt. As it
is, I have to switch to second gear even when climbing
minor slopes. It's as if I have a 600 cc engine !

The hose is connected properly. There are no other
hoses for emission controls, other than a short one to
the hot idle compensator unit. It's a very simple
carburettor, really, no requirements for emission controls
like the 4K-C unit in the USA. The carb for the 3K engine
is even simpler - no hot idle compensator, no idle stop
solenoid - just the vacuum hose to the distributor.

I emailed a complaint to Aisan in Japan mentioning
their poor quality control, but never got a reply. The
carburettor is definitely defective - I suspect that that
there is an internal vacuum leak inside. One can feel
and hear some "pop-pop" misfiring noises as the
throttle is revved up. Spark plugs and contact points
have been checked and are ok. I'm using the "High
Energy" transistorised ignition unit (kit) from Dick Smith
Electronics in Australia, with the points as a trigger.
The improved ignition performance compensates
a bit for loss in power due to the faulty vacuum advance.

I'm now contemplating building their programmable
ignition unit, which is basically electronic advance,
to link to the above unit, but I'm wondering where
to install it in the confined engine space - finding a
suitable waterproof box is a problem too. The only other
option is to lead it through the firewall into the passenger
compartment.