Idle issue

Replaced the carburetor about 2 years ago with with the OEM keihlin ,for some reason recently  the idle is not stable its surging, cant find any vacuum leaks and petrol and spark seems to be fine ,it sometimes idles perfect but when I blip the throttle the idle fall down to almost stalling or it starts surging, the choke youst to gradually increase idle as I pull it out but now it increases by only one level to a very high idle that sticks sometimes even after throttle blip. Any advice on what I should do ?oh and if I wiggle the actuator pump arm continuously side to side the idle increases by alot to kind of stable.

Have a look at the fuel metering. The seals can fail over time.

Sounds like a blockage in the carb, but its difficult to know for sure without proper diagnosis (ie lambda probe).

I replaced the fuel filter , mechanical fuel pump,and carb base plate,plugs today as good measure ,everything else is fairly new on the car did alot of work on this one for the past two years ,starting to think the problem lies with the actual carb theres really nothing else I can replace,i sprayed carb cleaner all over to check for any leaks and no change with the erratic idle or cutting out it.

Got the new carb today there are  3 vaccum ports at the back  which one goes to the distributor? And what are the other two for  ?

Is the bottom screw air fuel mixture ? And the top screw idle ?

Is it the same or different than the existing one (just 2 years old???) which is fitted? If its different, then what model is it?

If its the same then normally you'd just copy the existing connections. I think two of the vacuum ports can be blocked up (there are little plastic caps to do it).

I can't help thinking the existing carb just needed a bit of investigation and a clean out of the jets. At least the new carb was obtainable.

paul_c said

Is it the same or different than the existing one (just 2 years old???) which is fitted? If its different, then what model is it?

If its the same then normally you'd just copy the existing connections. I think two of the vacuum ports can be blocked up (there are little plastic caps to do it).

I can't help thinking the existing carb just needed a bit of investigation and a clean out of the jets. At least the new carb was obtainable.

It is different this is a pirate carb made by Dorco but the okes at the vw spare shop says this will run fine on a mk1 it was R895 . The exact one I bought two years ago was going for R1400 same price I paid two years ago , so I took the pirate carb instead this time so I can actually get the car running  again in the meanwhile ,and il rebuild and investigate the old carb when I get some time .Going to install this pirate tomorrow though  the 3 vacuums at the back took me by suprise but I see other people on the forum also have this one they posted pics  just wasnt sure what goes where on this one .

Sorry, not heard of Pirate/Dorco

Problem solved I ended up replacing the pirate carb with 3 vacuums for the more expensive one with two vacuums on the back one port had to be blocked and the other runs to distributor okes at the shop said it doesnt matter which port I use any at the back can go to distributor, this is basically the same carb as what I had it's made by arrowhead never heard of them before, everything  is spot on now,it just needed an idle adjustment .

In the old carb:
It looks like my choke mechanism might have been damaged  it is extremely loose theres no resistance on it at all when moving I figured it was flopping up and down while driving il tear down the old carb this week to check if there was any blockages or anything else that was faulty.

Thank to all that gave input !