Very bad economy

I have a 1.1C with 34 ICH weber. Im getting horrific economy (20-30mpg.)  It is running rich but there is not a screw on the weber to adjust this(?) only an idle mixture screw and that is almost all the way out (supposably making it leaner?)
Is there anything I can do to make it any more economical as its crippling me at the mo

SLOW DOWN!

 Ive only been driving 4 days, ive not been hammering around.

Hello Overmind,

If by "all the way out" you mean unscrewed (anti-clockwise) then this will make the mixture at idle richer.

You are correct there is no mixture screw for normal running on a Weber - that is why it's so important that the Jet sizes are correct (especially the Mains and Air Corrector/Emulsion Tubes).

Have you checked yours against the 1.1 Spec in the Weber Guide I sent you ?

Andy

Oh - and what do the spark plugs look like ?

If after a good run they are black and sooty - it's too rich.

Does it run OK ?

Andy

I was under the impression that the further out the screw was the leaner the mixture would be. I'll adjust this asap then.

I have checked it against the guide you sent and its the same so I dont think that is the problem. It does run well in my oppinion, it has never stuttered or stalled on me and it pulls well.

Economy has actually been better over the last few days. Im thinking it might have been down to the fact the car had sat around for 6 months prior to me passing my test and it just needed a good run.

If you have any other suggestions they are more than welcome.

Thanks.

overmind said

I was under the impression that the further out the screw was the leaner the mixture would be. I'll adjust this asap then.

If you think about it, it's a pointed screw in a hole (through which the fuel flows) if you screw it up (clockwise) it closes the hole and reduces the fuel flow at idle - leaner.

If you unscrew it (anti-clockwise) it opens the hole and allows more fuel flow at idle - richer.

Screw it in until it starts to run rough - then slowly out until it 'hunts' (is a bit more eager) and then set it between the two positions, slightly closer to rough.

By the way how are you determining that the economy is 'bad' ?

…and what do the plugs look like ?…

Andy

I have adjusted the mixture screw today and it runs a little better than before. I have only screwed it in slightly as anymore and it begins to 'hunt.' I also took the plugs out today. They were a little sooty but not nearly as bad as i thought they were going to be.
I thought with a smaller engine such as the 1.1 fuel economy would be around 35mpg, then again the 4 speed box doesnt do it any favours. The car smells rich on idle (excess fuel vapours in the exhaust.) However it doesnt appear to be running rich (spark plugs wernt too bad) so maybe its just something im going to have to get used to. :dontknow:

Cheers.

Economy is bad on mine WITHOUT the weber on!

tenner does me about 30miles id say, total estimation havent really been checking the milage but I only get about 3 days out of it.

blimey that is well bad me dads lexus gs300 with a 3.0 supra engine in it does 40 odd miles to a tenna

there is a mixture screw on that weber, u done electronic timing? theres a thingy for webers on google, download job.  sort air filter and a good set of plugs (with leads, good contact) do timing then mixture then tick-over

MK1_Arron said

Economy is bad on mine WITHOUT the weber on!

tenner does me about 30miles id say, total estimation havent really been checking the milage but I only get about 3 days out of it.

thats awful! thats like 15mpg! my scirocco 1.8 with a webber gets 70miles to a tenner round town 8O and i thought that was bad!

WOW that is bad, if i take it steady i can get 45 miles to a 5er!

Of all the mk1 cabrio GTIs i've had i would say that ?20 should do 140miles. Seems like the octane rating on normal unleaded is too low, so maybe running on super (shell 98) or using a fuel flush regularly would help keep at least a reasonable economy. Air filters, and whether its been serviced will all add up to make a difference.