Carburettor/weak mixture

[BillyBus]

I just got my van (1990 Automatic) back from a service and the mechanic reported a few problems with stalling after cleaning out the carb etc. He put it down to residual dirt, and thought he had sorted it by cleaning out the carb again. After a long run the van began to die at low revs, but was fine the next morning once the engine was cold.
I took it back to the garage today, and the mechanic took another look. He apparently cleaned out the jets etc again and told me that the van is now running on a really weak mixture but he can't get it any higher no matter what he does.
I really don't know what to think.
The van was having trouble starting in the wet before it went for the service, which I presumed was due to old leads. I had those changed, and that problem is now fine, it runs well...until the engine gets warm and I have to sit at low revs.
This is the second carb I have had (I got it from a guy who was breaking an old van about 3 years ago) because I had a problem with the original one from the van-which I still also have!
Is my mechanic missing something obvious, or am I just really unlucky

[toomanytoys]

either the jets are still blocked.. the fuel filter (one in inlet to carb and one at tank) is blocked (but where is the dirt getting in?? check all tank connections etc) or the fuel pump is on its way out and not supplying much fuel.. BUT in any fuel starvation case the fuel level in the float bowl would be low.... and you would notice this when removing the top of the carb...

Could be the idle cut off valve is not working properly.. this would give a weak idle and stalling....

[silverbullet]

While we're on the subject of carbs... now that I have all my property back I need to fix this:

Pierburg 2E carb damage.JPG

The white cam on the (primary?) throttle spindle has snapped off. Being as it's a rivetted assembly, where do I get a new one? Basic rebuild kits don't seem to include bits like that...
and yes I can see the split in the diaphragm rod end

[toomanytoys]

hijacker.....
answer............off an old carb...........

[silverbullet]

hijacker.....
answer............off an old carb...........

I'm cheeky, me! What? Gone NLA? I'll have to ask around, then

[BillyBus]

Thanks toomanytoys.
I don't think it is the idle cut off valve as it idles well and runs fine most of the time. It is only when the engine is hot after prolonged use that it will not hold. I think this is due to it running on such a weak mixture.
The fuel pump was replaced about 2 years ago, so I'm hoping that should still be good.
Seeing as I still have the original carb, I was wondering if that could be used for parts or anything?. Is the carb really even the problem here...

The garage seem convinced that the issues are:
A)down to dirt in the jets etc, and keep telling me that the pipes are old, but this has never been an issue before now, when the garage started poking the carb about.
B)down to not being able to adjust the mixture which is way to weak, again not a problem that was apparent before the service.
I gave them a bunch of fuel filters (as I had got a job lot online) and asked them to replace them as part of the service) and they are the same as the filters that were already in use. Surely this should be working to clear out any stuff in the pipes?

Is there anything specific that could have been done during the service that could have caused the problem?

Sorry for all the questions, but this is frustrating the life out of me. I don't have much tech know how, but I am trying to learn!

[edoh]

and yes I can see the split in the diaphragm rod end

snap! (oops wrong expression ) - i've got exactly the same on my carb - slightly worse in fact - as the top part of the plastic has split and snapped off -
will it badly effect the running of the carb? are there replacement parts?

to the original poster -

have you checked for air leaks around the engine? any signs of water in the petrol (see mr hulleys previous posts on this issue) -
is your distributor clean and secure where it sits in the engine block? and your timing good?

check the many other posts on the forum regarding 'stuttering' 'kangarooing' vans... a common sight round these parts..

[BillyBus]

I have just replaced the leads, rotor arm and distributor cap, so all should be sound there.
I had issues with water in the fuel a couple of years ago, so I know the signs for that all too well...not fun at all! This does seem to be presenting somewhat differently.
I've been out in the van today, just around locally, and it's been running perfectly!
I have been reading so many posts about carbs, and folk describing pretty much the same symptoms, but the solutions all seem to be different, or no solution got posted.
I feel an awful sense of Deja vu, since this is how I ended up replacing the carb last time..even then it was never established that the carb was even the problem.

Thanks for all the useful suggestions though. I will be jotting them down for my mechanic, assuming he does not have a nervous breakdown or run away when he sees me coming!