Technical Choke problem

[turbo_jim]

I went to look at a 1987 x1/9 for sale yesterday. It seemed overall in fairly good condition, but after being started it took about 20 minutes for the auto choke to cut out and the revs to drop to normal idle. While the choke was on, the car was undriveable, as it was running so rich it was misfiring.

Once it eventually warmed up the car ran fine. It had been standing for a week or so, and has previously been stood for about 6 months.

My question is does it just need the carb cleaning up a bit, or do you think there is a more serious problem. I dont mind cleaning the carb and giving the engine a service, but I don't want to buy a car that takes half an hour to warm up to usable condition!

Is this a common problem? Are there any other problems i should check for on a car that hasnt been used much?

Cheers

 

[ladaspeed]

It sounds to me like the choke is either stuck or very badly adjusted. Assuming it is a DTMR type, the easiest thing is to pull the whole choke assembly off the side of the carb, check for anything stuck, then put it back on - you will see the little spring fork that engages with the butterfly mechanism - if everything is cold and you put it back together with no pretension on then the choke will not actuate at all. you then need to wind the body around until the choke is closed, then wind a bit more, maybe half a turn or so. This will probably not be enough, but you can always wind it a bit tighter.

 

[jimbro1000]

If the choke did eventually turn off then the mechanism must be engaged - much more likely is that it doesn't have water flowing through the autochoke thermostat so it took ages to get warm enough!

Cleaning the thermostat (and the pipes that feed it) is easy enough. First of all take a note of the orientation of the autochoke, to make things easier there is a mark on the thermostat housing and a series of marks on the autochoke itself. Just disconnect the two hoses that feed it (makes sure you note which one goes where) and disconnect the housing from the carb - just three small bolts. You will lose some coolant but don't worry about it. Plug the joints in the pipes if you prefer.

Immerse the whole thing in a vinegar solution and make sure the pipes flow.

Let it soak - the vinegar will dissolve the chalk build up. You can use a citrus based agent instead it you prefer.

Put it all back on and then disconnect the upper pipe on the housing - you will need to bleed the autochoke otherwise all the above effort will be wasted. Start refilling the coolant back to normal level. Start the engine and begin bleeding it out as normal. If you jack the back of the car up as far as you can you don't need to use the bleed screw on the radiator the open pipe on the autochoke will suffice.

Once you start getting fluid coming out of the autochoke push the pipe back on and let the engine continue warming. Periodically just ease it off and let any air out - it will collect in the autochoke. Once you are satisfied that the engine has bled out you can tighten the last pipe clip up.

You can adjust how long the autochoke stays on for by rotating the thermostat against the autochoke (thats what those marks are really for). Sadly it doesn't mark which way you turn it for a longer application and I can't remember which is which...

ps. for reference it is a DATR carburettor not a DTMR (or rather DMTR).

 

[ladaspeed]

BTW Jimbro - I obviously didn't fulfill the criteria for GC as my registration attempt has not been acknowledged - but feel free to update the boys on there as I progress.....

 

[jimbro1000]

Thanks for the update - I will check with Guy and see what gives