Is the screw at the back of the 3PU meant to be sticking out or screwed tightly in? I'll try this after work tomorrow. Theres a bit of lead way for headless screw so that will help get the revs down. Just out of interest, what do I lose by not having the relay? Edit: Yes if thats the two way connector that goes in both orientations, the photo isn't actually my carb (probably should have mentioned that), the wiring is original on my scirocco.
Working by feel, I'd say my 3PU adjuster nut sticks out maybe 5-6mm outside the casting towards the firewall. My headless screw is a little less 'through' the plate towards the plunger than yours, maybe a mm or so less. It's a case of suck it and see really, if you get the headless screw too far through that plate you'll get excessive start-up revs (while the TTV is spoiling the vac to the 3PU, and making it fully extended). Try to adjust the nut on the back of the 3PU 'til the plunger sticks out about 8-9mm at idle, see what the revs are like, if too high, adjust the screw carefully. The relay was an attempt to improve economy by closing the throttle completely on the overrun, to stop any wasted fuel. I don't know why they stopped fitting them, or when, but my car certainly never had it, as the relevant socket in the fusebox where it would go doesn't even have all the necessary wires connected up to the back of it. The brown/black wire on my carb connector goes direct to earth. Might be that customer reaction to the accelerator pedal moving underfoot was too negative, or perhaps they discovered that the 3PUs were wearing out faster than expected (more stress on the diaphragm). Edit: seeing your edit, you'll have to see if there's another 10A fuse blown, as your TTV (item 11 in the diagram of post 4) really needs that 12V, and the same fuse powers the little heater low down on the front of the carb. Often, the wire to this little heater shorts out to the mounting bracket when the insulation fails, taking out the fuse (on CE1 electrics). On CE2 electrics, it and the TTV are unfused, so can take out the ignition switch if there's a short. Linky
Revs are good now. Although when cold it runs at idle and as if it's on 3 cylinders, until it's a little warm 50 seconds or so I'll check for that fuse when it stops snowing
cables on the carb Hi guys, trying to work out how to wire up my carb, as there is a loose cable hanging. in your picture of the carb, there is a red and white cable that goes under and round the back of the carb, and im sure has a plastic female connector on the end of it, same as mine! where does this connect to? mine is just hanging. plus on the front of my carb there is a connection missing, the what i think is a sensor to the left of the pull down unit. need to find the lead that goes to this.! my knowledge of carbs is about a day old im afraid. cheers for any help!
The fat red/white wire in that pic is, I think, meant to connect to the manifold preheater, AKA 'hedgehog'. You should see a similar-thickness wire dangling off the bottom of the inlet mani right at the back near the firewall, with a matching/mating connector. The sensor on the front of the carb, from your description sounds like the overtemperature thermoswitch, if the car and carb 'match' there should be a wire for it with the appropriate female 1/4" connector on the end of it, but don't worry if you can't find it. That thermoswitch is more a luxury than a necessity. Is the carb the original, or a transplant? If a transplant, the original may not have had the thermoswitch, so the car wouldn't have had the wiring for it. Post some pictures, that always helps.
