I can see it has ben a long while since Constantin made the last comment on this topic. I have done all possible tests to my Pierburg Carburettor 2BE fitted to a BMW 316, 1986. All the circuits are correct, the measurments of resistance and voltage are qithin the specifications. Well, there are a couple od resistances that are outside the range. These are located in the plug of the throttle positioner. As you know, this devise controls the iddling speed. And for those who are familiar with the problems associated with this issue, once the iddling speed starts to go wrong it is 99.9% due to a fault in this part of the circuit. One only needs to add the appropiate resistance to put it back withing the specifications and the iddle speed will work almost smoothly. But that is not the problem I have. This is tio do with the mixture. To give you an idea as to how bad it is, after having run for 60 - 70 minutes the spark plugs become so fouled that the engine stops. I have to take out the spark plugs and clean them to make it running again. Naturally, to avoid damaging the engine I have stoped starting it and let it to run for longer than 30 seconds. I have even adjusted the only screw one can manually handle (the mixture screw) and no matters if it is fully open or fully closed, the mixture remains obscenly reach. Even the wire harness to the Electronic Control Unit has been checked. All is perfect. What it could be? Is there anyone who could shed more ligt on this nightmare? I can only think on the only part I have not checked as I have not the means to do it. The Electronic Control Unit. There are places in the UK where one can send the ECU for testing. Cost is £60 P&P incl. But I haven't found a garage or else in London who provides this service. Can anyone tell me where there is one in London? Most appreciated.

Thanks. As I have said, I've checked every single item on the carburettor and they are all perfect. The float was the forst thing I checked. I even changed the needles just in case. But the mixture remained the same, too rich. My only doubt points towards the ECU.