RESOLVED-1.5L auto 1981 mk1 running rough - pierburg 1B carb

Hi all,

I have been having trouble recently with my mk1. so i thought id put it on here, hopefully someone can help.

When the car is cold and upon starting it cuts out, but if you block of the return fuel line it doesn't cut out, could this be an issue with the fuel pump?

Once it gets warm It idles fine and smooth (just under 1000rpm-1300rpm) but does seem to be running rich.

However upon putting it in drive to pull away it looses its revs and has cut out a few times, im having to over rev to stop this happening.

When driving along it splutters,coughs and judders all over the place, theres a certain lack of power when putting your foot down although it does seem to come back with hard acceleration.

So far I have:

-Replaced the fuel filter
-Replaced the plugs
-Replaced the dizzy cap
-Replaced the rotor arm
-Reset the points based on the brown haynes manual
-The timing seems correct

Here is a picture of the Pierburg 1B carb



The carb seems very wet, however this might be from the autostart.

And here is a picture of an overview of the carb



Do you think it is likely to be a carb issue, a timing issue or something else?

Hopefully someone will be able to help.

Thanks.

I had a similar problem with mine a few years ago where it seemed the car was running out of fuel, first check all the connections in you fuel line my fault took me ages to find and the problem was that the plastic exit on the fuel purge reservoir (the black plastic reservoir after your fuel pump) was kinked over but it appeared ok with the hose attached it was only until the fuel line was removed that it became apparent.

To check you fuel pump when running you should feel/hear it ticking away as its a mechanical pump if in doubt remove the fuel line and turn you car over, you'll see the fuel shooting out lol

Thanks for the reply Lee.

Ill give your method a try to check the fuel pump before I go ahead and order a new fuel pump, but ill try and catch the petrol

Did your car only cut out when you tried to pull away? Or did it try and cut out even when idling?

Looks like ill have do spend quite a while investigating pipes then.

Also did you have a fuel return or was yours capped off?

Hi my return was not capped off, but mine only cut out under acceleration or high speed as if it was running out of fuel.

The purpose of the purge reservoir is to control fuel pressure to you carb when too high it feeds back to the tank when too low allows to the carb. In the end I replaced mine with a bias t piece as I couldn't repair or find a new reservoir.

If you find none of this works then you might be looking at taking your carb off and cleaning it, it's a fairly easy job too. Have you looked at the colour of your spark plugs?? To see if it over/under fuelling etc this is a quick and easy check for running problems.

Hi was just looking at you pictures and I think I've found your problem!!

You have the fuel line the wrong way round. The current sent up is sending all you fuel back to the tank not the carb swap your fuel lines around as shown in the picture below:




let me know how you get on.

lee

Thanks for your reply, Ill give that a try when I get home tomorrow.

Me and my friend looked at that and wondered if it was the wrong way around, but couldn't find anything in the brown Haynes manual to tell us what the correct way around was so we left it as it was.

When I picked up the car I drove it home about 50 miles with no trouble…with it the wrong way around haha, So god knows how I made it back and god knows why the previous owner had it set up wrong.

But anyway ill swap them around and ill post back here how I get on

Thanks for your help.

The pipes have been swapped round.

And I have been trying to get the car started but I haven't had much luck.

The car starts and doesn't cut out if I rev it, however if I step off the accelerator pedal the car just cuts out.

I even let the car get warm..and it still did the same.

I have taken the fuel pipe from the reservoir and placed it into a bottle  to ensure the petrol comes out and it does.

Any ideas what i should try next :/

Looking at the carb in the picture below, should that flap be open or should it be closed? I assumed that's got something to do with the choke?



Im guessing that I probably need to alter the idle mix setting on the carb, as maybe with the pipes being the wrong way around, the carb was set wrong.

Any suggestions on the above?

Thanks.

Hey soz for the late reply been busy,

yes your correct that butterfly flap is for the choke and as the car warms up it should gradually open as you have an auto choke fitted.

Sounds like the same problem that I had a few years ago. You can try stripping the carburettor down and blowing all the needles and idle bleed holes out with an air line, but however this never solved my problem I ended up buying a direct replacement weber carb with an manual choke. I would say that since the car revs like mine did but wont idle it's a carb issue as you clearly have fuel, air, compression, and sparks. The only other thing you could check is that you have valve clearances as this can affect the cars running if there too slack or tight.

Soz I can't help but I never managed to fix mine and I got fed up of messing around with it so i brought the weber and ever since the car pulls better and runs spot on doing 5000 miles a year, just about to clock 150,000 miles lol.

If you wish to take the carb off its only two 10mm bolts, I personally give cleaning it a try first as this is the cheapest option.

Thanks for the reply

I messed around with the idle adjuster screw and have since managed to get the car to idle, even though it is pretty erratic, going from around 800 and occasionally dropping to 100 then jumping up to around 1100 rpm then back down to 800 ish.

And if I put her into drive, the revs drop off but the car doesn't cut out..however I don't know if that's meant to happen when you try and pull off, that the revs intentionally drop.

If I spray carb cleaner into the adjuster screw, this increases the revs for a short period..I'm not sure if that means there is an air leak with the adjuster screw seal?

The weber

I looked around online for ages to try and find a "weber carb 36 tlp" to replace the pierburg, but they seem really hard to get a hold of

The choke flap doesn't seem to move at all, even when the engine has warmed up. So it looks like ill be taking your advice and removing the carb from the car and stripping it down.

Ill also check the valve clearances.

The only other thing I can think of would be to modify the auto choke and add a manual choke with a switch in the dash..however that's way above my capabilities haha

I can see how you got fed up with your pierburg.


Does everything point to the carb and maybe the auto choke not working correctly as the choke flap doesn't change?

Could there be an airleak with the adjuster screw seal?Or does the increase in RPM when I spray the carb cleaner into the screw just mean there's a leak with the carb somewhere?

Resolved now.

Thanks to  everyone who helped out.

what was the issue with your car then pal? same issue with me but i have been told that the carb needs a rebuild

The solenoid on the front of the carb wasn't getting the 12v that it needed….for some reason it was wired up to a heat sender…oops.

So I attached it to the coil and voila, it works fine now.

The only issue I have now is setting up the carb, as the adjuster screws have been messed with.

I'm not sure if I should take it to a specialist to get the carb setup spot on, or just try and do it my self based on the pierburg carb book I have.

Did you get your carb sorted in the end?

wind mixture screw (right hand side, a pain to get to without a long skin flat blade) till the car hunts, wind out half turn, car should stop hunting.

set idle speed to between 800 and 1000rpm.

are you still on points?

Thanks for that novocaine, Ill have a play with that later if its dry.

I need to set the idle to around 800-1000 when the cars got up to temperature don't I?

Yeah still on points.

yes once engine is warm.

ditch the points.
google for powerspark. will make your car runner way better.

Thanks, is this what you mean:

http://www.simonbbc.com/electronic-ignition-kits/volkswagen-golf-mk1-powerspark-electronic-ignition-kit-jfur4

One thing I have noticed is that when the cars In reverse the idle drops to around 100RPM, have you any idea what might be causing this?

nearly.

your car will have right hand points I think.  :wink:

bad earth maybe?  :dontknow:

eBay for the win:

http://www.ebay.co.uk/itm/Bosch-POWERSPARK-Electronic-Ignition-Kit-k6-/130725700410#ht_1052wt_932

Surely this is the right one

Ill check for a bad earth if it stops raining

double check which way round your points face first.