revs high and strange cable !!

[Tony Tone]

Maybe a coincidence, maybe not though.

I had the air filter off today where it joins the carb. put it all back together and ran the engine.

It all ran all great for 20 mins, then the revs went very high. I made sue the throttle linkage wasn't stuck , it wasn't and it was in its resting position. It tried altering the adjust screw, it made no difference at all.

I then took the top off the carb again. The choke flap is almost closed ( is this right), and I also found this weird cable hanging about, what is it and might it be the cause of the rev problem ?.

cheers, Tony

I've attached a pic of the odd lead

[Ian Hulley]

The 'strange cable' is used by VW for telling where top dead centre is. Leave it alone and no drama will occur The choke flap is where it should be.

Ian

[Tony Tone]

Phew, thought id unplugged something serious there. How would you suggest i get the revs down ?. Theyre about twice what they should be at idle. It was running fine on tickover and then up they went. Cant rdmember if i revved the engine and they went up and stuck . The throttle cable is slack though . Help ?!?!?

[Ian Hulley]

Higher revs is usually extra air getting in OR something stuck open.

[kevtherev]

or it's cold... and the fast idle is working correctly

as it warms the revs will subside

[Tony Tone]

I ran it for 20 mins so it was all nice and hot, itcwas then that the revs went up, not down as they usually do, most odd !!!!

[kevtherev]

spray the fast idle cam with some wd 40 just incase it's sticking.
if it was hot then the choke flap should be open, or was that taken cold?

[Tony Tone]

The picture was taken when all was hot. The flap was nearly closed

[kevtherev]

The picture was taken when all was hot. The flap was nearly closed

then it's very wrong tone.
can you move it with your finger?

[Tony Tone]

Yes, the flap can be moved easily by hand to the open position. When left , the flap sots almost closed except for a 4-5 mm gap.

[kevtherev]

Ok This is the difficult bit..
when you move the flap you need to see why it doesn't stay open when hot.
if you take the autochoke spring housing off, three screws, the spring inside will come off with it
you will then see the dog that fits in the spring.

Is the spring intact?
does the dog move when you move the choke?
Was the dog engaged with the spring?

spring

dog

[Tony Tone]

Presumably this sits on the right of the carb as you look at it?, can it be done with the carb in situ ?. Ill have a look friday and be back .

[ermie571]

from experience...yes and yes

Em

xx

[Tony Tone]

Is the dog the white plastic bit at 12 o clock ?. Does this fit into the squared end on the spring ?.

[kevtherev]

yes.
then you can adjust it as you can see.
rotating the housing clockwise will open the choke flap earlier.
be careful though, too early and the engine will stutter from lack of choke.

A good yard stick is when cold and engine off, as you depress the accelerator the cam should flip round and open the fast idle throttle.
after starting it should rotate anticlock to the next step, and so on till warm, all the time the spring is opening the flap and this takes about 6-8 mins to open fully

you can see the cam here, on the top step, this is the cold start position



there's also a little lever that operates the flap, if the flap does not move with the dog then this may have come off
you can see the bottom of it here



here's a little video of the spring operation