Intermittent cutting out

[ticket2ride]

Ok, need to start my own thread on this with the hope of sorting it out.

I have had a problem with the van cutting out when slowing down. Ive read lots of threads: 1, 2, 3, 4, 5...etc which tend to fall into fuel delivery, air leak, electrical fault (inc coil).

So far Ive been haphazard at trying to sort it out. One mechanic I took it too on holiday in Devon said he thought it was air leak at spindle on carb, which is Pierburg 2E3. He greased it as a temporary fix.Think this was around the Part load enrichment valve, part 24 here. I have not had this apart to rebuild it. He also said the vacuum advance doesn't work. He was too busy at the time so I didnt get him to fix it and haven't yet had it done.

Last year I removed the fuel tank and replaced it to rule out fuel contamination. The filler neck was perished so went overkill and changed the tank. I checked breather hoses were ok and replaced seals at same time. Stupidly I did not secure the filler neck properly and it came loose and couldve contaminated the fuel again.

I replaced coil with another used one. I know what the resistance should be but havent done readings as I don't know if I can do it on my £5 multimeter:

So I don't know if either the old or new one good/bad.

Also I have 2 fuel filters, an extra one in the engine bay.

So....today Ive started trying to do this methodically.

Removed the conical filter in the carb:


It looked clean.


Then did Ghost's fuel delivery check. Think this is a spurt rather than a dribble:
T25 fuel pump

If this is ok I don't want to fit an electric fuel pump just for the sake of it.

What next? Check coil properly? Have carb rebuilt, get vac advance replaced?

Thanks in advance.

[HarryMann]

Why are you avoiding sorting the vac advance out when this could be a prime candidate. ..
If you advance the timing a good chunk say 15 degrees and drive very carefully (to avoid detonation) does it still do it?
That's one test if you can't fix the vac advance

[HarryMann]

..and most multimeters can measure resistance in the range you need.

[ticket2ride]

Why are you avoiding sorting the vac advance out when this could be a prime candidate. ..
If you advance the timing a good chunk say 15 degrees and drive very carefully (to avoid detonation) does it still do it?
That's one test if you can't fix the vac advance

I bought the powerspark vacuum advance replacement but couldn't get the distributor off because the bolt was seized. Likewise, cant do your test until I can move it. Will spray some plusgas on tomorrow and have another go at it. Not sure how hard they are to fit if I manage to remove it. It might be a garage job.

I will post a picture of trying to read the coil resistance tomorrow.

Thanks for your replies.

[CovKid]

Sounds like mech in Devon was about right although if vac advance not working that could well be leaky, further compounding potential for air ingress at carb, weakening mixture and causing it to die.

[ticket2ride]

Sounds like mech in Devon was about right although if vac advance not working that could well be leaky, further compounding potential for air ingress at carb, weakening mixture and causing it to die.

How hard are those carb rebuild kits to fit? I took the top off my 2E3, cleaned the jets and put a new float chamber gasket on. I couldn't figure out how to disengage the accelerator to remove the bottom half. Would like to refurb it myself. Happy to pay a garage to check mixture & timing.

[CovKid]

Not hard to refurb it. Last kit I got was about £40 (ebay) and it did help with running but I suspect you have more than one issue anyway.

With engine running (if you can get it to idle off choke), try spraying WD40 around throttle shaft and see if revs pick up significantly. If theres a leak it will temporarily plug it and revs should rise. Shaft may be fine and a good clean out and regasket may improve things considerably. However, they may not if there are other problems elsewhere. You MUST sort the dizzy vac out - I'd say thats the number one job before you even consider tackling carb.

In very simple terms for an engine to idle accurately it must have a measured and predictable mix of air and fuel. At large throttle openings the engine won't care much but as soon as you drop to idle both the timing and fuel/air mix HAS to be right or it can die on you. If diaphram in dizzy vac unit is gone, it can suck in a lot of air from there for starters. Don't mess with idle/mixture screws - find the leaks if there are any and sort them. Try removing pipe to dizzy from carb and suck on it. If you can keep sucking air through it, so can the carb. With dizzy cap off, when you suck on that hose the plate inside dizzy should move and you should be able to hold it there by temporarily putting the tip of your tongue against the end of the pipe. If you can't, its split/holed inside.

[ticket2ride]

With engine running (if you can get it to idle off choke), try spraying WD40 around throttle shaft and see if revs pick up significantly.

This is what Ian at South West VWs in South Molton did. I heard the revs pick up when he did it. He said there was an air leak on the spindle.

I think it probably needs at least a new gasket to the manifold as it looks very grubby there:

Try removing pipe to dizzy from carb and suck on it.

Ian also did this. It's how he diagnosed kaput vac advance.

You MUST sort the dizzy vac out - I'd say thats the number one job before you even consider tackling carb.

Will do. Is vac advance easy to fit if I can get the distributor off?

I realise now that I should've proceeded with the most likely cause.

[CovKid]

https://club8090.co.uk/forum/viewtopic.php?f=39&t=138696" onclick="window.open(this.href);return false;

Read that too.

[what2do]

Replacing the vac advance unit is so quick and easy that I barely had time to drink my tea whilst Itchyfeet changed MINE My van had been running like a bag of spanners prior to replacing it - boom, like a new engine once it was done.

[kevtherev]

If the vac advance diaphragm is punctured then two effects will occur
No advance and air getting into the induction side as said.

[CovKid]

Over the years I worked on far fewer points based distributors but certainly one item which I had no real time for during those years was the 009 'all advance' distributor which lacked a vacuum unit. I still don't recommend them except where an engine has been custom built from the bottom up. With a 009, you basically set it to a max of 29 degress with the engine revving its nuts off. It sort of works (in a fashion) but lacks any refinement beyond that despite the fact it tends to be marketed as a performance item - go figure.

Anyway, I mention this because the vac unit plays an important role, enabling the timing to respond to changes in pressure within the carburettor itself (ie different throttle positions), making the whole set up more responsive at different engine speeds. With a dead vac unit there is no shift in timing and the spark gets out of step resulting in very poor performance indeed. The vaccum line basically sucks the diaphram inside the vac unit. Attached to this diaphram is a rod in the distributor which moves the distributor plate round in a reasonably coherent fashion. With a split, old or leaky diaphram, no vaccum is to be had, the spindle stops moving properly and the vac line is then just sucking in air - to the detriment of idle mixture. In fact if the vac unit is definately dead, although it won't cure it, plugging the vac pipe may stop it cutting out. It'll just have poor acceleration. Unfortunately what tends to happen is folk mess with static timing or mixture screws to compensate - not good.

You can see the effects of a good vac unit by connecting it and unconnecting it and using a timing gun to watch the static timing marks. With no vac unit on a stock dizzy, the marks barely move. On a 009 they move in almost a linear 'rough and ready' way and with a stock dizzy with working vac it is more progressive and a lot more responsive. With computers added to engines this has been improved further and helped to improve MPG.

In your case I would suggest that along with poor performance your MPG won't be good either. With a leaky vac line, as soon as you come off the throttle that extra air is making the mixture so lean, it cuts out. Additional leaks could be from bottom gasket rather than spindle but if spindle needs rebushing talk to Roger Ball as he does mail order rebushing at very reasonable cost (you fit new gasket kit). A new vac unit, new bottom carb gasket and you'll probably be a lot happier. Alternatively you could swap the carb for a good secondhand one I suppose.

Was trying to explain timing to my lad when I took him into school. The best I could come up with is its the gap between when you throw a match and a puddle of petrol goes 'Whumph!!" So the faster the engine goes the earlier you have to chuck the match - thats the 'advance'.

[what2do]

May I just add point, both myself and Itchyfeet have (must be careful how I word this ) tested the same unit by sucking on the pipe, he manages to get the arm in the unit to move but I cannot due to lack of (extra careful how I word this) sucking power!! In all seriousness, it may be worth getting a second person to do the test before determining a result. As I said further up, my unit was shot but it took Itchy's lungs to prove it.

[CovKid]

Two of you sucking in duet you mean

To be fair, it shouldn't be that hard to suck enough to pull the arm in unless dizzy plate is clogged with old grease/muck or vac unit knackered. Had I remembed this as a boy I wouldn't have lost the ball when playing blow football, but thats another story.

[HarryMann]

... the main effect i was thinking of with the vac advance is when coming off load the ignition advances considerably which increases efficiency but importantly speeds up revs & clean running when idling.
Its actually better to picture it oppositely; as timing being retarded when coming under load...
If ign. timing is set correctly it is thus likely idle will be slow & unstable if vac. adv. stops working.
It could just be a stuck plate as suggested though not sure how common this is.