Club 80-90 Forums

van starts and funs purfect, better than it has for a while, think thats the weather, but every time i take my foot off the gas the engine cuts out, not just when i come to a stop but just by the revs dropping, problem did not cure itsself once engine was warm

due think its the idle speed or somthing else. no other issues

have cleaned the carb as best i know how and have tried adjusting the idle speed screw, at least i think it was, please some ideas please before it goes to the £65 vw garage, thanks

Well you don't say what engine you've got but presuming its in good order, things that can cause this include poor connection to electro cutoff jet on carb, air leaks (beneath the carb, around the carb) and anywhere on inlet port. Are all vacuum pipes secure? Are they breaking up? Is the mixture too weak?

Try spraying WD40 around potential air leaks and see if idle steadies or increases in speed. You may find a culprit there. Wear in carb throttle flap is a known prob going back to my earliest bug days. Engines don't like leaks on the inlet side and a VW running at the low revs it does, hates it even more.

thanks covkid, ill try n make my way through those suggestions but im sure im not capable enough,

its a watercooled 1.9 by the way

hi belle i had a terrable three weeks of vehicle cutting out. after 4 mechanics looking at it and a lot lighter in the pocket i decided to try redex fuel treatment as a last resort. as i did not believe in these products but after three tank fulls going through it i have a perfectly running engine try it for the sake of a fiver you might be as surprised as i was

cheers hammy44 i did a fule treatment also but havnt run it yet, will see tom

A compression check would show up any leaks around valves or elsewhere in the combustion chamber - thats generally what Redex is for. Takes a few minutes to do a compression check - if that is what is causing this.

I might be completely wrong here, but mine cuts out at junctions and if slow down on approach to roundabouts, when running on petrol. Been told I need to replace the pierburg pull down unit. Could it be that?

I can only say that every vehicle I've worked on in the Aircooled range that has had this symptom has been down to weak mixture or an air leak -sometimes a pipe off but usually the throttle flap. The latter problem was so common on bugs by the 80s, principally cos all the carbs had done a lot of miles and the throttle flap simply worn out, with so much play they were sucking in air from outside. At wide openings (ie when revving) this isn't so noticeable but as soon as you drop back to idling speed this extra air seriously affects idling. Satisfactory idling is a delicate balance between air and a slow drip feed of fuel against just the right amount of suction from the engine. Too much air (anywhere on the inlet side) and it weakens the mixture to such a point it just dies.

Given the fact that the T25 has been around a long while now - some as much as 26 years, its would seem a safe bet that the wear to the the throttle flap has caught up with the wedge. The good news is that any good engineer/tool fitter with an accurate lathe can remove the flap and stem, rebush it and refit. There isn't a great deal else to wear on carbs.

There are other reasons this can occur but the above was VERY common on bugs. Elctromagnetic cut off jets that are faulty or with a bad connection will also cause it.

Air leaks can occur at the inlet ports, at the carb gasket, throttle flap, or a pipe left off on the inlet or carb. Any leaks here and idling becomes erratic if not non existent.