Fuel system - 1.9 WBX stops intermittently
Qu. In extreme cold the 1.9 WBX will run for approx. 1 min then cuts out and refuses to start again, it is turning over but not firing
Check the carb heater is working, and working for as long as it should.....
I have carb gaskets and pull down units on the shelf if needed. Sounds like normal Pierburg carbs done a zillion miles type problems, not too hard to sort out but I deal with them weekly. Quite a simple carb if you know what your doing.
Last one I did like that however, like stated was a combination of poor maintainance, thats the trouble when "Sunday morning man" does his own as he misses things a mechanic will spot. Check fuel line for being porous, not the long plastic one, they never go wrong so don't even think of replacing that, the other connecting pieces that go onto it. Make sure lines aren't kinked anywhere. Check the small guaze filter thats shoved up the carb fuel inlet pipe isn't blocked. Check fuel tank and filler neck for corrosion and anywhere where water can get into the tank. Replace fuel filter anyway, aforementioned water just bungs fuel filters up. Check pulldown unit diaphragm isn't blocked. Usually when they get a few miles on their back the fast adle needs adjusting up as they don't adle as fast as they should when the choke is on.
Have had similar problems with a pierburg 2e3. My difficulty was that it would start and run ok on a lot of occasions (the choke mechanism was not working so I had to keep a foot on the pedal during warm up) but then it would refuse to start at all from cold at other times. So it's not exactly like your problem but...
...there was a combination of problems aside from the choke not functioning. The fuel filter was overdue for replacement so it was struggling to draw fuel. On examining the carb, the float chamber was found to be full of muck. The power enrichment valve chamber was full of the same, and the gasket between the upper and lower carb bodies was pretty much shot. I realise that none of these (except possibly the fuel filter problem) accounts directly for your problem and your point re choke pull down might be relevant i.e. if there is insufficient vacuum to adequately open the choke flap whilst engine is idling from cold so it floods. It's taken me some time and serious reading to get mine sorted. I've currently got a Carb book out of the library which is very good so if yo want me to scan something and send it to you, let me know. Mocki's comment re the heater is relevant, (I know from previous posts that he is a carb guru so I bow to his advice) I didn't realise until I left the ignition on by accident whilst i was testing things just how much it heats up the throttle body and surround.
If the vehicle has been stood for some time (ie months), you may struggle to get it running at all. If it will start with a dash of petrol down carb throat but not by normal means, and pump (electric or mechanical) seems to be working as it should, proceed as follows:
Remove top of carb carefully so as not to damage gasket, and check that float needle valve isn't stuck/wedged shut. Its in the top of the carb above float - look and you'll find it. It should move up and down with the float. Even slight corrosion between needle valve and bore can render it stuck, meaning incoming fuel is diverted straight to return line to tank instead of into float bowl. This can easily happen with a dry carb. Incoming fuel generally lubricates this valve and prevents corrosion or even limescale but if left dry, it can become stuck shut. You can use VERY fine emery paper to clean the ridges on the needle (but go easy). The bore can be cleaned with brasso but make sure NO grit is left behind.
To gain access to the needle valve, you'll need to knock float retaining pin out. The needle valve is attached to the float with a tiny hook.