this is another mystery to me about fuel consumption in a carburetter 1.3 engine.

all started with a rough idle and a hissing/gargling sound from top side of carburetter with the air filter removed. ok, so that was a clear sign of vacuum leaks, maybe some gunk inside carburetter. I bought a new rubber flange, Haynes for Pierburg 2E3 manual aside, disassembled and thoroughly cleaned the carburetter with carb cleaner in every orifice, lock, stock and barrel.

I put all together and idle was smoother than ever, but... I got 15 MPG :S which is 3 times worse than normal. so I said, maybe the choke doesn't fully open after warming up. being summer that time, I locked it open mechanically. but no luck. what else could it be? maybe the float level is not right? so I changed float, needle valve and checked the level, checked the needle valve is closing, all was ok. but again... 15 MPG. wtf?

the only thing left was a fuel leak somewhere before carburetter. ok, that called for drastic measures, so in order to rule that out I attached a 2 liter container under the bonnet, and 2 hoses: one to fuel pump input and the other to fuel return connection and went for a test... guess what? 15 MPG

then I looked at spark plugs and I was expecting to find them wet-brown, but no! the insulator color is almost white, showing a LEAN condition

THIS CAN'T BE. what am I missing ???

P,S. the 15 MPG "performance" was measured outside city, max. speed 65 mph, gentle accelerations.

Edited 30 December, 201114 yr by masster

At least can you tell me how much is a new Pierburg 2E3 in UK and where could I boy one?

maybe the fuelpump is leaking the fuel into the oil (they used to do this a lot!!) or if it has the green fuel pipe it used to go porus and leak everywhere. 15mpg is really not good and the fuel must be going somewhere as even in the rallycar it would do around 9-10mpg and that was working the engine very hard.

doubt you could even get a new carb now but maybe someone has some old stock?

Thank you for reply. I checked many times for leaks in the engine compartment, under the car where I park it, and never seen any sign.

On the other hand, if I had a fuel leak into oil, with such high fuel consumption I'd have the engine seized in no time for oiling on 'fuel', not to mention the engine would probably blow up from fumes and extra pressure. Dipstick check shows clean oil, it was changed some 400 miles ago.

Finger crossed for extra stock.