Dr. BMW, what is your diagnose

[bassej92]

Dear e21 enthusiasts,

I've been driving (and working on) my '77 e21 318 for about three years without major problems. However, my car recently failed and I can figure out what to do. Because of this reason I am asking you for your help. I worked on some motorcycles before, but the LPG (gas) installation isn't making it any easier for me. I am starting to think that a more modern car might be better for me!

The problem; I can only start the car on petrol at the moment. It starts very difficult and only runs on high RPM. When I lower the throttle the car will stop running and it'll thus not run stationary. Also, the carb leaks petrol after it stops running. (Itś difficult to find out whether the car runs on all four cillinders, but it should be able to run on three if there aren't any other problems.)

My first thoughts are that it gets too much fuel, because of some sort of leak. I don't know about the LPG-related problems that exist and could arise so please help me. Also the carbs are somehwat modded to fit for LPG and I don't know what's normal or abnormal. Where should/could I start??

Thank you in advance

[Peter V.]

First welcome.

You can devide the LPG and petrol thinking. First start by making the petrol part right and then look at the LPG part.

What is modified to run on LPG, only a flange between the carb and the manifold or does the LPG inject in the airfilter?

* Have you done work recently and the problems started then?
* The petrol leak is mostly a bad floatingdevice/needle in the carb. This in combination with a bad gasket there.
* Put some pictures or video on the forum so we can locate the issue better please.

[bassej92]

Thank you!

The LPG system is the flange thing you mentioned. I was thinking of the floater in the carb, I saw that problem very often on vintage motorcycles.

I had not used the car for a few months but it then started without any problem. Now, after 200 km or so I have this problem. Itś just a little weird to have these things occur spontaneously.

[bassej92]

cleaned the floater needle and it runs again... So easy, though such a pain in the ass when it happens at night!

[Peter V.]

You must be running a lott at LPG so the dirt from the fueltank can be your problem. When you then run on fuel the dirt which is in the fuellines comes loose and gives the problem. Check the filter also then.

Nice that she is running now.

[bassej92]

Nice, I will clean it.

Are their any fluids (to be mixed with the petrol) that can clean and maintain those parts? I use about 30L of petrol per year I think

[nas80]

when you leave petrol in a tank it turns into a gum. you might want to take the tanks off and flush them, you may have corrosion in there and rust is blocking your petrol?