a Specialist kind of nightmare

[BOXY]

Sounds like a fuel problem. Check if you're still getting a spark when it won't fire. My money would be on a choke problem.

[Tony Tone]

There certainly is a spark as the engine fires but wont idle. I can keep it running by revving constantly ( not gentle pedal pressure)but as soon as I take my foot off it dies straight away. Why would it run totally ok for ten mins then just stop and then not idle ( it will fire)

[BOXY]

Could be the auto-choke not coming off and flooding the engine when it's warm.

[Tony Tone]

Hey boxy, it could be , would account for when i leave it 30 mins itll restart and run fine, then get warm and cut out. However, the engine installers tried a second engine and the same fault appeared which would suggest its van not carb ?.

It also appears that the replacement engine has a later carb etc than my original, would there be a carb / wiring mismatch here ?

[kevtherev]

OK some basics required here.
What carb is on?.. should be a Pierburg 2e3

Depending on the carb, if it is a Pierburg, does the choke flap open?
To see that you must remove the duct on top of the carb, and look.
Now this isn't your carb so we'll just concentrate on the flap covering the Venturi

you should see this on a cold engine



and this on a warm engine



it takes about 6 mins to get to the latter from the former

[BOXY]

installers tried a second engine and the same fault appeared which would suggest its van not carb ?.

Did they definately change to a different carb when they tried a different engine? I'm afraid all my hands on experience is Aircooled & twin carb so I'm not sure how a DG choke works? Didn't someone mention a possibility that the carb heater & choke wires were switched over? See if you can confirm the choke is working how it should be. (Like Kev just said)

https://club8090.co.uk/wiki/Pe ... burg_Choke" onclick="window.open(this.href);return false;

[Tony Tone]

Hey Kev, I've posted some pics of my carbs wiring here:

http://s1270.photobucket.com/albums/jj6 ... /Facebook/" onclick="window.open(this.href);return false;

It is a 2e carb, pic o the link. When the engine is hot the flap is definitely open.

Tonight, and as last night....runs for 10 mins from cold, shuts off wont restart, will fire but not tick over. Leave it a while, fires up, ticks over for a few minutes and then dies again returning to the above documented cycle.

I'm leaving the van overnight to see if the flap shuts as I had it running when I checked my messages

[kevtherev]

OK
Stalling, unable to tick over when hot is a weak mixture/ worn fuel pump or maybe timing.

Have you looked at the possibility of air getting into the induction side, from these points

1. the brake servo hose (braided type)
2. the choke pull down unit diaphragm
3. the secondary throttle diaphragm
4. inlet manifold carb gasket.
5. inlet manifold head gasket.
6. Distributor diaphragm
7. fuel pump actuating rod worn.
8. fuel pump delivery

just some pointers for you to contemplate

[Wychall]

Just a thought from an uneducated WBX newbie. Would using an exhaust gas analyser be any assistance to identifying what changes as the engine gets warm? Something must be changing at that point to cause the cutting out. My thoughts are that an air leak will be weak throughout, not just warm. Fuel pressure could be a problem and that this would show as a reducing CO2 level as the mixture weakened. Timing could be checked as to present setting then advanced or retarded by experiment. Is the advance controlled by an ecu or by balance weights? (Told you I didn't know WBX at all!)

[Tony Tone]

I'm informed that the engine installers tried fitting a perfectly running DG into my van as they just couldnt get rid of the problem, and when they fitted it, it had the same problems as my van !, this is most puzzling, unless of course they didn't fit it. They also tried another carb too, apparently. That said, you can set your watch by the point that it konks out and it happens very time, 10 mins running, then dead, give it a while and it restarts and ticks over.

I'm really puzzled by it but shall check all of the possible air leaks, I'm assuming it would have to be a single big leak or an accumulation of small leaks.

Could it be electrical, some mix up with the fuel solenoid etc ?.

I now have a different ecu thingy and the carb is a differing type to the one originally fitted, or at least I think it is.

[BOXY]

I can only think of a couple of things that haven't been mentioned already that might be (and it's a big MIGHT) causing the stalling after ten minutes.

1) Is the exhaust choked? Is it possible the engine is gradually building up back pressure in the exhaust a stalling the engine?

2) At the other end is the fuel tank / cap vents blocked so the van is creating a vacuum in the tank and gradually starving the engine of petrol?

I was going to say that the engine stalling after ten minutes points towards something failing as it warms up / gets hot on the ignition side, but as you've still got a spark that rules everything electrical out.

[Tony Tone]

So, i shall try running the engine with the fuel cap off tosee if it addresses any vacuum issues and will check for collapsed fuel lines to the carb also. If this fails im coming to the conclusion that the engine fitters ( supposed specialists) disnt try two carbs and a complete engine from another van and i need to look at getting a new carb or at least another one to see if i can effect any change.
Roll on tonights experiment !

[Tony Tone]

Re electrical and warming up. If I restart the engine once it has cut out, it fires but will not run on its own. It will however keep going if I keep revving the engine constantly.As soon as I stop revving, it cuts out.... does this help ?.

[MartinR]

I've got a'86 dg with standard Pierburg. After years of this being in the family I started to get the usual cooling problems so spent some time sorting out just how things interconnected. I realised that the wiring around the carb was incorrect (and had been for years - ever since we had it). In essence the manifold heater had no power feed.
So, I reworked the connections to give it a go. From cold the van was much smoother, but about a mile and a half down the road it cut out, and as you say it would start and could be driven if bullied.
I came to the conclusion, as the only thing I'd changed was waking up the manifold heater, that it could be the culprit - either the temp sensor not working or the relay (41? from memory) in the black box on the front bulkhead, left side, of the engine compartment stuck on. I pulled this relay and everything reverted to running as It had for last god knows how many years .
Symptoms sound similar - worth a try?

[BOXY]

The fact it kept running when you rev'd it is what made me think it could be a choke problem. By rev'ing it you're opening the throttle and overcoming the choke by letting more air in.

Have you tried running with the air filter off so you can see if the choke flap moves during the 10 minutes before stalling? (have a fire extinguisher handy in case it pops back and spits fuel at you).

Like I said before I never touched a DG carb but after reading the wiki and manual I think there is an idle cut-off solenoid that cuts off when the ignition switches of. If that works the way if sounds you would need a 12v feed for the van to run. If your carb is losing this signal for some reason maybe that's what's cutting the fuel at idle? Try find this connection and test it for 12v with the ignition on. Slave a bulb off it to earth and see if the light goes out when the engine stalls.