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Mk2 Stalls when idle at any speed


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NebulaicToaster

I put in a new mount a few weeks ago and she ran fine. Then I was replacing a rad hose and today driving her she was fine but kept stalling when idling, off the throttle, even in 3rd gear at 30. Pulling up to junctions you have to keep the gas on or restart the engine. What could be wrong?

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What's the choke flap doing? is it nearly closed tight with engine closed, then opens a fraction when it starts? If not the pulldown unit could be split. Rare. Or choke mechanism could be st

Update! Blasting the idle jets with canned air has made the cutting out upon acceleration go away! I'm not going to speak too soon, I haven't driven it yet just revved. Also it could be the cold weath

Yippee. Though I hope you are now not stuck in the middle of nowhere.   The pulldown unit pulls down a lever attached to the choke flap to crack it open a fraction from fully closed, so it t

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I am no expert, but it sounds like a fueling problem, did you disturb the inlet manifold carb flange. They are a notorious problem for air leaks. Try wiggling the carb on its mount to see if the revs rise or fall. If that proves to be the case, you will need to ensure the mount flange is spotless, and use a new carb flange gasket. They go hard and brittle around the intake. The last time I looked for one for my car, they were no longer available. Hopefully there is a wealth of knowledge to come to your aid here, from the forum.

 

Good luck with it☺

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NebulaicToaster

Yeah sorry I was in a hurry typing. I replaced the rubber inlet manifold carb mount the other day (for the second time, the bolt holes for mine have been terrible quality) so I don't think it's that. I might have overtorqued the bolts though, can someone double check the official torque for me please, my Haynes is unreliable sometimes. It's a pierburg 1b

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NebulaicToaster

Well shoot. Just went to drive home. Idle was lumpy but now she won't start at all. The coil, cap and rotor arm are new. I left my bloody spark tester at home. Maybe the carb vacuum has completely gone?

 

EDIT: I managed to get picked up. Will drive over in my reliable car tomorrow with toolbox, timing light, spare HT leads, rotor arm, cap, coil, dizzy, plugs etc that I have knocking about. I've got a new base mount (my 3rd now!) on the way and some new bolts (m6x100) on the way too. This Pierburg has given me so much grief. I'm starting to wonder if the bolts I took off the scrappy polo with a 1b are even the right size, or if the basemounts I'm buying have different size threads to m6. I tried using some m6 bolts I had about in the original perished carb mount and they went right in but I remember the bolts off the scrappy car didn't thread in easily, lots of resistance I thought was supposed to happen in order to hold the carb in place properly. That might explain why the thread glued into the rubber mount came unstuck. Maybe I should search for a weber at the scrappy instead (any idea what type I need?). I just want to drive the ruddy car!

Edited by NebulaicToaster
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NebulaicToaster

Could do with some help on this one. Think it must be carb related. I've got the old girl to start. The car idles fine now. The base mount isn't leaking but any acceleration above idle it either cuts out when revving up or on the comedown. I've done this while holding the carb down. I've sprayed cleaner in (that helped for a little bit) and I know I'm getting spark when it's cutting out so it's not that. It is almost like the carb is starved of fuel. The fuel filter is sloshing about at idle so I assume it's working. Any ideas appreciated. The car is stuck in a pub car park for a while :(

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What's the choke flap doing? is it nearly closed tight with engine closed, then opens a fraction when it starts?

If not the pulldown unit could be split. Rare.

Or choke mechanism could be stiff seized.

 

Or the needle valve might be blocked or worn.

But that tends to give really tough starting behaviour.

 

If spraying cleaner helped it might be the pilot jet (or its circuit) has a blockage.

 

Search for 'RAC patrolman trick' on here. You put your hand over the carb throat at idle and rev it by pushing the throttle quadrant to use petrol sucked by engine to wash the part blockage away.

I usually resort to a can of compressed air keyboard cleaner, but I have also used a bicycle pump with washer fluid tubing. I now carry an earwax bulb syringe that was a couple of quid, is sealed in sterile clean packaging and survives -10 to +40 degrees C. 

Or unscrew the tiny pilot jet with correct fitting screwdriver, hold it up to light to see whether is clear and blow through it if not. Don't drop it, lose it or put anything in it.

(Well - to be honest -I've used a toothbrush bristle and a sharp wooden skewer, but only because I had a spare jet)

 

In the cold weather you might need a tiny bit more richness. That's anticlockwise a halfturn or less on a mixture screw (or clockwise a quarter or less on an idle bleed).

 

 

Edited by dvderlm
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NebulaicToaster

 

7 hours ago, dvderlm said:

What's the choke flap doing? is it nearly closed tight with engine closed, then opens a fraction when it starts?

If not the pulldown unit could be split. Rare.

Or choke mechanism could be stiff seized.

 

Or the needle valve might be blocked or worn.

But that tends to give really tough starting behaviour.

 

If spraying cleaner helped it might be the pilot jet (or its circuit) has a blockage.

 

Search for 'RAC patrolman trick' on here. You put your hand over the carb throat at idle and rev it by pushing the throttle quadrant to use petrol sucked by engine to wash the part blockage away.

I usually resort to a can of compressed air keyboard cleaner, but I have also used a bicycle pump with washer fluid tubing. I now carry an earwax bulb syringe that was a couple of quid, is sealed in sterile clean packaging and survives -10 to +40 degrees C. 

Or unscrew the tiny pilot jet with correct fitting screwdriver, hold it up to light to see whether is clear and blow through it if not. Don't drop it, lose it or put anything in it.

(Well - to be honest -I've used a toothbrush bristle and a sharp wooden skewer, but only because I had a spare jet)

 

In the cold weather you might need a tiny bit more richness. That's anticlockwise a halfturn or less on a mixture screw (or clockwise a quarter or less on an idle bleed).

 

 

My pierburg has a manual choke (got it off a MK1 fiesta for peanuts to replace the auto) so choke isn't a problem. I'll give the RAC and idle jet tips a go, is there a particular number of screws in the jet needs to be? Also, it's the middle one, right? (http://www.gowerlee.dircon.co.uk/1B3type.html think you posted this a while back, very helpful diagram)

 

What does the pulldown unit do? I'll take the one off my old carb with me to test.

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NebulaicToaster

Also, could a lack of swirl pot (my manual choke 1b came with feed and return brass tubes) be causing air bubbles when revving, which might be why the car cuts out above idle? I've got the old swirl pot so I might give a go blocking off the carb return and using the swirl.

If it is the needle valve, I've got a spare, how easy is it to replace in situ? I'm still stuck in a pub car park

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NebulaicToaster

Update! Blasting the idle jets with canned air has made the cutting out upon acceleration go away! I'm not going to speak too soon, I haven't driven it yet just revved. Also it could be the cold weather unsticking something, I stupidly didn't test again before doing the idle jets. But in theory I'm no longer stuck. Cheers, this forum is bloody ace

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Yippee. Though I hope you are now not stuck in the middle of nowhere.

 

The pulldown unit pulls down a lever attached to the choke flap to crack it open a fraction from fully closed, so it turns over very rich then starts about 11:1 Afr not 5:1 which just makes soot on your plugs so it stops running.. 

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NebulaicToaster

Got her home fine, I was tuning up with a colourtune and although it's really a bit sunny to see blue I'm having trouble. Very light throttle makes it go lumpy and cut out but anything above is fine. Any idea what that means, too rich/lean?

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On ‎16‎/‎02‎/‎2018 at 08:04, NebulaicToaster said:

it is the needle valve, I've got a spare, how easy is it to replace in situ? I'm still stuck in a pub car park

Stuck at a pub is not the worst that could happen.

 

Needle valve fault would show as awful hard to start, not that it won't continue running.

 

Procedure should be fuelline off, carb top off. Lift out carefully to avoid damage to floats or gasket, split pin hinge for float  out - I've only done that on Weber where you have to push sideways from one end - not sure about Pierburg. Retire to warm pub. Unscrew needle holder. Fit new. Finish pint (of lemonade).

Refit in reverse order. Check float droop by holding top perpendicular to ground until float arm just contacts needle top. Bend float arm if not correct. Then readjust idle.  

 

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1 hour ago, NebulaicToaster said:

Very light throttle makes it go lumpy and cut out but anything above is fine. Any idea what that means, too rich/lean?

Probably what you dislodged from jet is broken up and is now at the idle mixture screw.

So count how many turns to bottom out the screw (gently). Unscrew it completely.

There's probably an o-ring. This might need replacing after this.

Look at the tip and clean it with carb or brake spray.

Blast can of air from top. Some fuel may well come out of the mixture screw hole.

Then with a soft tube back up idle mixture hole. It should bubble in the well.

Refit idle screw.

All the way in and then out the number of turns you counted. 

 Then back to colortune.

 

 

(all written assuming good ignition system, fix that first)

Edited by dvderlm
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NebulaicToaster
19 hours ago, dvderlm said:

Stuck at a pub is not the worst that could happen.

 

Needle valve fault would show as awful hard to start, not that it won't continue running.

 

Procedure should be fuelline off, carb top off. Lift out carefully to avoid damage to floats or gasket, split pin hinge for float  out - I've only done that on Weber where you have to push sideways from one end - not sure about Pierburg. Retire to warm pub. Unscrew needle holder. Fit new. Finish pint (of lemonade).

Refit in reverse order. Check float droop by holding top perpendicular to ground until float arm just contacts needle top. Bend float arm if not correct. Then readjust idle.  

 

I just drove to Wells and back, an hour each way, and Birtha is running brilliantly. I didn't have to resort to needle valve replacement but this is a very useful reference for the future. You've been so very helpful! I'll try and get some pics up in a build thread later on. Cheers

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NebulaicToaster

So I drove 400 miles to Wales and back in the polo over the weekend. Somewhere near the half way back the idle problem returned. Turns out the bolt on one side had shaken the fittings out of the mounting and for 100 miles I drove her using the engine vacuum to stick the carb down without realising. Not good.

 

Anyway I had a spare mount because I suspected it might go again and I bought new bolts too. With those fitted the car now idles fine but 0-4mm of throttle will make it go lumpy and cut out. This also means a cut out when pulling up to a junction. When I took the idle jet out and sprayed air down then put it back in it ran fine but the problem has returned this morning. I'm going to try a spare idle jet to get me home but then take the top off and check for blockages. I'm stumped at this point

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NebulaicToaster

Are there any other symptoms of fuel pump dying? I've got a spare so I could replace

1 hour ago, dvderlm said:

... could be fuel line blockage or fuel pump dying?

 

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See how fast it fills a container while cranking ?

Think Haynes has the delivery rate.

(with ignition disabled eg plug removed at Hall sender  or with no spark plug king lead in coil. careful that no spark will ignite open fuel vapour)

 

Or remove and operate the pump's plunger by hand. See how much you get per stroke.

Cam's movement of plunger is quite small.

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NebulaicToaster

I'll give it a go when I've made it home, she is a bit hesitant at low revs in gear too. Slightly stuttering at 25-30mph in 3rd gear sort of thing. Fine once the revs are up though. I would wager it's a compound of fuel pressure and a blockage in the carb

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NebulaicToaster

Fun little update, got to a hill nursing her home. Had to stop because of traffic, knew she would stall. No dice with starting again. Luckily after ten minutes some policemen helped push onto the flat. AA on the way. Can't get it to start. Carb mount is solid. Maybe this dizzy (new) has gone too? An unlucky week so far. 

Edit: it's snowing now

tmp-cam-1860691843.jpg

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Ah, bad luck. Keep warm and safe.

Which force are the coppers from? That's worth a thank you letter.

 

Does mixture screw need to be just a bit further out...for the cold weather?

I also added a shield to cover half the radiator to make it run a bit warmer.

 

 

 

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Carb icing will reduce power, but not stutter in my experience. Unlikely for dizzy to fail. 

Any sign of igniting (engine catching when turned over)? no - electrics, yes - fuel.

 

Once for me the king lead at coil was corroded because moisture had flowed down cable past rubber boot. Golf mk2 mounts the coil horizontally and away from road spray. Good dose of Wd40 to drive out moisture, then wiped, cleaned/emeried all connectors  and sealed with some Holts Dampstart Autoplast.

 

It goes crinkly and doesn't look great, maybe hair lacquer spray would do the same.

I think it helped cold wet starts and journeys.

Edited by dvderlm
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NebulaicToaster

My AA man turned up and did much of what I already had but with one key difference. He flipped the fuel filter. It was in with the flat end facing towards the tank and cone towards the carb so possibly chucking grime into the carb and reducing flow. He chucked some AA carb cleaner in and blew through the filter, also checked the spark with his little gadget (quite nice, better than my timing gun). He followed me home and the problems returned. I fully cleaned out the carb, took the top off etc in the warm of my home. Fully cleaned and back together I put it back in Birtha and put her in the garage. Tomorrow I'm going to get a new filter and tenderly drive her down the road. If the problems return I'll try the pump or just put in the pierburg I got from the scrappy. A peculiar day but hooray for the Wiltshire fuzz

Edited by NebulaicToaster
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NebulaicToaster

So I fitted a fresh filter (the correct way) this morning and took her out to warm up enough for a colourtune. All was well it seemed, pulling well and idling out of gear. Pulling into my drive however (a slight incline) the dreaded happened and the engine stalled. Stuck on the slight hill I couldn't get it to start so I dragged her back the the garage with another car.

 

Given that hills were involved twice, it seems vaguely fuel pressure related. The filter seems to be empty while running but will fill up once stopped. Is it the fuel pump perhaps or maybe a blockage further up the pipe? My pierburg 1b manual choke doesn't have a swirl pot because it's off a fiesta, could blocking the return and fitting a swirl help? I'm rather stumped with this. Cheers. J

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So the AA man helped any captured crap on inlet side of old fuel filter to flow into the carb. :unknw:

You need to test the pump..

 

 

I wonder if the float is sat too low.

Certainly on Webers going up an incline causes more fuel to cover the emulsion tub holes as these are slightly offset to rear of the well by design with float hinge pivot facing direction of travel. (I once drove with a reverse mounted DMTR from Golf - fine in the flat fens of East Anglia).

 

A swirl pot needs a return or the pump will overcome the needle valve and flood, It's just a means of removing bubbles. A large accumulator before after pump

(I use a motorsport fuel filter) might help.

 

 

 

Edited by dvderlm
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