I've been fiddling with my 2E2, specifically the secondary pull down unit. At first I thought it wasn't working as I tried revving the engine quite hard to see if the secondary choke flap moved - it didn't. I then disconnected the hose and connected my vacuum pump to it. With the engine off, I moved the primary throttle to fully open and then applied vacuum. This time the secondary flap moved. When I relaxed the primary throttle the secondary flap started closing almost immediately. This would suggest that in order for the secondary pull down to come into play, you've got to have your foot to the floor. Of course I couldn't test this in the car park as without an engine load the revs would be far too high. Question is - how do I test that it's working in 'real life'? Also, is there an adjustment for when the secondary pull down starts to act i.e. how far open the primary has to be? In my haynes it refers to a stage 2 vacuum control unit which is fitted to 1.6 manuals and 1.8 autos from 1984. Who has this? It would seem to be a 'tweak' to the secondary pull down unit. Cheers all.
Start off by dropping the term pull-down as that'll get you confused to start with. More of a pull-up if anything? Pretty sure there's a cam on the primary throttle assy that disables the secondary from doing anything until there's 50% primary throttle open i.e. 45 degrees-ish. Not adjustable IIRC, but possibly something's broken/adrift? Have you proved to your satisfaction that the vac feed hole in the primary venturi is unblocked? Could be the diaphragm is leaking, and the vac pump is failing to hold vac cos of that? Stage 2 vacuum control unit is what you're calling the secondary pull-down unit. I would guess that you are getting confused with the two-stage operation of the choke flap pull-down unit. Stage 2 here refers to venturi number two, the bigger one.
Too late! I must admit to being a bit confused with secondary/pull-down and stage 2 descriptions. My own fault for speed readings bits under my desk when I should be working I'll have a look on my spare to see how open that needs to be. If I can hold the vacuum and then open the primary I should see both move which will give me a better view of the angle it needs to be. No. I'm getting some carb cleaner from Halfords on the way home tonight. I'll give it a blast en route and see of there's any difference. I don't think so as I did the 'tongue test' on my spare and that held it, but it descended when I used the pump. I'm wondering if the pump needs lubricating somewhere to help seal it. A re-read in order I think. I'll try and dig out my carb manual too. Cheers
i had those questions like you. and i tried to test stage 2 unit on parking, well it is impossible, even guys on forum explained to me. i test it on other way, plastic pipe that goes from back of carb to termoswitch on airbox, disconnect it on termoswitch on airbox and connect it directly on sta 2 unit. and immediately you will big vaccum presure and revs will go to about 3.5K. and you will have overfueling in engine with black smoke on exhaust. true is when stage 1 is about 95% opened than cam unblock stage 2 butterfly and it can be opened to its maximum. this is my video that i have tried that when stage 2 is opening. http://www.shex.max.net.ba/carb/Video183.mp4 you can reffit cam and make it open earlier, but when stage 2 is opening early than cam other side of that cam do not allow stage 2 butterfly to open to maximum that was the main problem. i have test this. you can test it and see when you pull you carb off. another test that i made is that i just disconnected stage 2 unit and try to run, and let say revs from 3K are very poor, acceleration is very poor like diesel. when you connect it goes really faster on higher revs. it is to test it check that video please.
