Hi - started my stock 74 1.8 ljet yesterday after rescuing from its winter tomb - ran like a charm so thought I'd shine it up. Today (of course) being sunny and warm its starts up and runs like a pig. Chugging at idle, sooty exhaust - suspect it is running rich - any one have any ideas where to begin? I see lots of advice re lean running on Ljets due to vacuum leaks as the cause but this?

Is there a simple way to check the cold start valve is working when it should and not leaking ie how do you isolate it? Any help much appreciated

when does it run crappy?
whats your ambient temp?
does it run well at start up then as the engine warms begin to smoke and idle poorly?
best way to test it if you think the cold start is bad then you should be able to just unplug the injector.

check the air filter.
if you have a vac leak you would have a rich mix at idle and it would lean out to the correct mix as rpm is increased.

did you touch anything in the engine comp when you "shined her up" ?
Andy

thanks - will check that - as for the cold start valve - want also to be sure it just isn't leaking - I guess I can just unbolt it and crank it over (?)

Some winter crud dislodged into the fuel filter?

http://manuals.type4.org/ljet/