poor fuel consumption - issues with carb?

[ryleybob]

Hi,
I have only driven my 1981 316 for a little while now and am surprised at the poor fuel consumption I am getting - 13 litres per 100 km. I never expected it to be great but that is much worse than I expected !

I think (hope) that the engine itself is in very good shape - genuine 106,000 km (one previous owner) with BMW service book. The car was last serviced by an independent mechanic 1,000 km ago. The engine doesn't smoke and sounds very sweet when warmed up idling. The car is completely standard.

While taking it out of the driveway today I noticed that the idle was running very high (there is no rev counter but it sounded as if the automatic choke was fully on). I revved it once and it settled down. I then noticed intermittently similar high revs (as if the choke was fully on) when idling after the car was warmed up. Again it then calmed down.

[Jeroen]

Sounds extreme indeed. It might require a little check up of carb settings, exhaust gas test, check for vacuum leaks (carb base gasket is notorious) and while there you may want to have ignition timing and ignition vacuum advance checked as well.

[polov8]

My 316 is excellent on fuel, but it's running a weber direct replacement carb DMTR otr DMTL, I forget which, with a manual choke. I would definitely check the choke functions properly, and thall the things that Jeroen has suggested.

[Jeroen]

Fingers crossed!