Just taken delivery of a 1989 MK2 that's been sitting for a year. The guy said there was an auto choke problem so he'd included the manual conversion kit (just a cable from what I can see, does it need any brackets?) But the issue isn't the choke, she starts but revs up to full and stays there. The throttle isn't stuck but I can't figure out what is wrong. It could be a rogue idle screw but I'm yet to find which screw is which on a diagram. The Haynes manual does the solex carb, any insight would be appreciated. (Pic may help)

Cheers,

J

The choke flap is fully open and there are no hoses to the two pipes of the auto-choke on right of carb in that picture.

Is this with engine at operating temp?

I'd guess that the warm up phase has been set to to be over-rich (air bleed on side screwed clockwise) because the flap is open so that once warmed up there is too much fuel.

 

Racing engine at idle is also symptom of vacuum leak and the rubber carb mount is the usual culprit.

Check out ruddies berlin website for Pierburg 1b instructions.

http://ruddies-berlin.de/se1B3VWe.htm

says fast idle is around 4000rpm at warm up. We are just all spoilt by injection engine management.

Edited 10 September, 20179 yr by dvderlm

That link is very helpful, I'll have another stab at it next weekend and if needs be service the carb completely. The fast idle might well be what was wrong. Great to finally have a clear manual for the thing. 

Cheers,

J

So I got hold of Pierburg 1b with a manual choke  from a MK1 fiesta that was in good nick the other day, it's identical to the polo pierburg bar the manual choke mechanism and an additional fuel return pipe. I gave it a proper clean, redid the seals and fitted it. I also replaced the rubber carb mount (which was a fiddly job and the new mount didn't let the carb bolts tighten completely so I put in a couple of temporary spacers).

 

It has stopped revving up to max constantly but now the car won't idle. She runs up to full revs then dies down to nothing. This video might illustrate it better (sorry for potato quality, I'm reaching in through the window to turn the key, no throttle is being applied)

 

No idea what the problem could be, maybe a distributor problem (unsure of what to look for to diagnose). Any help would be much appreciated! 

 

Sidenote, is the idle adjustment screw at it's highest revs when screwed all the way in?

Edited 20 September, 20178 yr by NebulaicToaster
maybe a dizzy problem?

PS: www.clubpolo.co.uk/topic/261155-mk2-13-dying-problems @dvderlm I've just had a read of this thread you helped someone with back in 2011 and it looks like I could be having similar problems. The new carb I put in had both supply and return pipes so I did away with the swirl pot. Your other thread suggested it wasn't quite as useless as one of the FAQs suggested so that might be causing my problems (maybe the internal fuel reservoir is running dry). If I put it back in can I just leave the return pipe open (or plugged) and attatch the swirler to the supply pipe like the original pierburg had? 

 

Cheers for all your help

Yeah, swirl pot is a good idea to remove bubbles and give fuel somewhere to go when needle valve closes when reservoir is full.

Fit a pipe and block it with a bolt and jubilee clip on new return outlet.

 

Not idling. Insufficient fuel, too much air.

 

If I remember right the 1B has a idle fuel screw in a corner that has an emission protection cap and should normally not need fiddling with, and an air bleed that screws opposite way to a fuel screw, so anti-clockwise weakens.

 

I'd suggest getting a colortune spark plug to set mixture right. 

Did old carb have tubes to a box on bulkhead? If so that's an idle stabilization valve control that this engine needs as idle speed will wander.

Never completely explaiened I think flywheel is too light on this engine.

 

 

Edited 20 September, 20178 yr by dvderlm

You've not done anything to distributor. So not that.

 

Could you have you overtightened rubber mount bolts?

Many nowadays have threaded inserts that are not well bonded.

I'd trust Febi or Spa brand.

It's possible the underneath bolts are too tight, and it's also possible that the guy I bought it off fiddled with the dizzy (he claimed the starting problem was auto-choke related but clearly that isn't the issue) 

It may be worth noting I couldn't get her to idle by holding the throttle down a quarter reliably

Yep so it turns out I put the fuel in and out lines the wrong way round when I put the carb back in after doing the seals. That explains why it wasn't idling. I feel a little silly  but I'm happy it's working now. The idle is still pretty high unless the choke is on (it's my first manual choked car, i've dealt with tractors and such and they don't need much. How long should one keep the choke on, the car must warm up fairly quickly?) it sounds like when I open the choke it's putting more revs on, the choke pivot does look like it can push something connected to the throttle, maybe I need to adjust that too.

 

I've ordered a colortune kit, so I'll give that a go when it arrives. Very satisfying to be able to pull her out of the garage without a push now.

 

I'll have a look at the FAQ for advice on leaks, it looks like i've got one under the tank (probably a line) and one front driver side slightly back from the alternator (no idea).

 

Cheers for all your help so far! I'm learning a lot

More likely a pulldown unit which opens the choke flap from fully closed (alomost no air only fuel) to a few mm open (so more air) when engine fires for the first time and priduces vacuum as each piston descends with inlet open.. There will be a specified amount called something-klappenspalt in german that ruddies should provide.