5 replies to this topic

[disco5619]

A potted history of my car is that ever since getting it back on the road 3 years or so the engine has taken 3 or 4 miles of running with choke fully out to warm up and settle down. Maybe 2 years ago I had problems starting which turned out to be the electronic spark system in the distributor and the car ran great for the following 6 months. Now I seem to have to keep the choke out fully at all times and the engine will falter and cough and backfire if I push it in. Now I am using the car infrequently and only short distances this is the fault I had some three years ago which would eventually clear when the engine was fully hot and I had travelled 10 miles or so the choke cold be fully pushed I. And the return journey after the longer journey would be travel free.
The car is a 1989 mini 30 998 cc and I have had the engine tuned by a mini specialist locally some 2 years ago and I have the electronic ignition fitted to the distributor and Lucas plug leads and dizzy cap.
The car will start ok from cold and run ok until I go to push in the choke than a misfire comes and the engine runs erratically under load . The car will tick over ok but when I try to pull away the engine falters and tries to cut out until I pull the choke out .
My understanding seems to point towards a carb problem i.e a sticking jet but I would like some other opinions before I get my hands dirty trying to find the fault.
If you could spare me some time and give me some suggestions I would be very grateful.

Chris D

[Batmini]

Is the car up to temperature before you push the choke in? Are your plugs in good condition?

[Wim Fournier]

I think you have a problem with false air. When air is sucked in after the carburettor, then there is no fuel in that air. So, you have to pull the choke fiercely to get the engine started. After running a time the engine reaches a temperature and by expansion of the metal the air leuk closes (almost) for as long as the engine is on running temperature.

So, check the tightness of the manifold against the engine head and the tightness of the carburettor against the manifold. Try tightening the nuts. May be you need a new manifold gasket.

It is also possible that the PVC (positive crankcase ventilation) is not air tight. So look at the connections of the rubber tube at the carburettor and at the oil separator or at the rocker cover. Is the tube not ripped.

Tell us the result, so we can help you further when this is not solving the problem.

Edited by Wim Fournier, 13 November 2015 - 04:22 PM.

[carbon]

Sounds like it's running a bit on the weak side. But do check Wim's suggestions first.

 

If the carb has been set up so the car passes MOT emissions then it might benefit from lowering the main jet height very slightly.

 

What colour are the sparking plugs?

[Blatherskite]

I think you have a problem with false air. When air is sucked in after the carburettor, then there is no fuel in that air. So, you have to pull the choke fiercely to get the engine started. After running a time the engine reaches a temperature and by expansion of the metal the air leuk closes (almost) for as long as the engine is on running temperature.
So, check the tightness of the manifold against the engine head and the tightness of the carburettor against the manifold. Try tightening the nuts. May be you need a new manifold gasket.
It is also possible that the PVC (positive crankcase ventilation) is not air tight. So look at the connections of the rubber tube at the carburettor and at the oil separator or at the rocker cover. Is the tube not ripped.
Tell us the result, so we can help you further when this is not solving the problem.

Try also spraying a thin oil (wd40) carefully around the joints mentioned by Wim. If any gets sucked inside, you should hear the engine speed up - and there's your leak.

[gazza01]

Carb rebuild me thinks, and make sure it's cleaned through properly rather than just renewing the supplied parts.