I have a 1983 533i and have been having problems over the last several months which feels like it is not getting enough fuel. Both fuel pumps have been replaced and the problem has been greatly improved and the fuel filter has been changed several times. (The in-tank prepump was actually not functioning.) But I still have a similar problem. For the first five minutes or so the car runs great. Then there will be a slight transient hesitation. With time the hesitations become more frequent and stronger. It feels like the engine is starving for fuel. Pressing harder on the gas petal will get it through this temporary crisis, but in a few minutes the hesitation will return.

Any ideas?
drmark

btw, I changes spark plugs, rotor and distributor cap a couple of months ago.

Do you have a fuel regulator?
I have no experience with older bimmers.

I assume a fuel regulator is the same as the fuel pressure regulator? If so, the answer is yes. The fuel pressure regulator is located at the opposite end of the fuel injector rail. A replacement is $70 and I did consider just replacing it. But I am not sure if the fuel pressure regulator would be the cause of problem. However, I am not that knowledgeable about such things.

dr mark

The fuel pressure regulator could be the cause of the problem. I don't suppose you know what fuel injection system the car has? It's probably one of the Bosch Jetronic systems (most 80's Euro cars did). You can check the fuel pressure at the rail. This will tell you if the regulator is bad. Don't just go replacing parts hunting for the right one. This gets expensive fast. Check the fuel pressure first. If that's good, it's possible that the injectors need a good cleaning (how many miles are on the car?). You can get this done at http://www.rceng.com/ for $24 per injector. It's worth every penny. I'd be more apt to suspect the injectors need cleaning than the regulator is bad.

Thanks! I do tend to agree with you that it is probably not the fuel pressure regulator (that is why I am hesitant to buy a new regulator even though it would be very simple to replace), but I will have the fuel pressure checked. I have been suspecting that the injectors need cleaning. My hesitation with this is the intermittent nature of the problem. When I first start the car and for about 10 minutes or so, it really runs great. Initially the hesitations are quite subtle and minor and progressively get worse. For example, yesterday I drove the car for several relatively short errands and it never once did this hesitation. Turning the car off even for 10 minutes seems to make the problem go away temporarily. It seems to me that dirty injectors would present more continuous symptoms.

In regards to your other questions, I do not know the what type of fuel injectors it has off-hand and I do not know the exact milage. The odometer was broke at 127K when I bought the car about a year and a half ago.

mark