405 1.6 carb issues

My 405 1.6 GR 1991 H reg now judders when cold and on odd occations dies and
then jumps again? almost like a fuel starvation and then instant fuel surge?
any ideas as to a cure welcome.

 

Check the obvious - air filter, spark plugs, spark plug leads, distributer
and rotar arm, fuel filter.

I did find severe starting problems with my old carb 1.6. Found out that
after a coolent change I had not topped up correctly. The auto choke hose is
above the rad fill level and was not operating properly and there was an
airlock in the system.

Once I had established correct levels I had no further problems with cold
starting.

Any problems passing the MOT emissions test? Another reason could be a worn
carb.

Otherwise its checking idle and co levels with a tune up.

 

these carbs are notoriously bad
new one is usually crap too
check and see if weber replacement with manual choke is available
if not then try a manual choke kit
also check for excess play in throttle spindle which causes an airleak
failing that older 406's are cheaper now and far superior

 

Apart from fuel economy, which is really terrible, I did not find the carbs
unreliable. The auto choke worked well and I did 122K in my first petrol
405. ( scrapped due to a HGV rambo pikey b******, who failed to stop after
running me off the road)