accelerator cable/auto choke/carburettor problem?

joeroach · Post by **joeroach** » Mon May 08, 2006 5:11 pm

recently my BX 19TRS estate has started accelerating of its own accord intermittently. the revs begin rising up to about 40-50 00 rpm when in neutral/with the clutch down. lasts for about 10-15 minutes then calms down again. still drivable but a bit tricky.. Has now happened several times - just after starting, but also on the motorway/ mid journey. have checked accelerator cable and doesnt seem to be sticking anywhere- possibly the auto choke or carburettor?

Way2go · Post by **Way2go** » Mon May 08, 2006 5:17 pm

Check your return spring on the choke aperture butterfly is OK.

ellevie · Post by **ellevie** » Tue May 09, 2006 12:57 am

I had something like this on my 19TRS hatch a few years ago; very disconcerting. Mine has a Solex carb with a black square choke housing. It turned out to be the linkages situated between the choke housing and the carb; once they were cleaned and oiled it worked fine. I would also check that the 2 inch spring-loaded drum that the cable attaches to still has the spring wound around it in tension.

Hope this helps.

joeroach · Post by **joeroach** » Wed May 10, 2006 5:17 pm

the spring controlling the choke aperture butterfly appears fine - not snapped or anything, but perhaps is slack.. the butterfly is in an almost vertical position. When pushing the two ends of the spring together, closing the aperture the engine calms down. Should I simply replace this spring or is there any other method to control the aperture size- perhaps a screw on the carb?

Way2go · Post by **Way2go** » Thu May 11, 2006 2:43 am

It is probably not the spring but maybe a misadjusted/missing screw for the throttle stop or idle adjustment. Check the linkages surrounding the aperture butterfly and the accelerator linkage.
You could check the spring itself by taking it off and seeing that the coils touch each other but this is a weak spring usually by design so unless it is stretched or distorted it is probably OK.
Sounds like you are very close to spotting the problem!