89 240DL 2.3 manual with carb and choke

Hi all, this is my first post. Joined the club on the basis of what looks like a great site for info so perhaps some of you guys can help me with my queries please.

I understand from my garage that my carb is worn out because they cannot adjust the mixture screw any more? Don't know what to ask them to enlighten me more or whether there is any easy fix?

Next prob: From cold I set out and join the motorway about four miles away. Do about six miles at around 65-70 and then car looses power, smoke like fuel being burnt is apparent through the rear window and eventually it stops. So, switch off, wait a moment or two and without the choke the cars starts and drives as if normal. This comes and goes, doesn't happen every time I use the cars. Any thoughts? Someone suggested new fuel pump and he thought at times the pump was oversupplying and car couldn't burn fuel and chokes to a stop. I don't smell petrol at this time.

[Erling]

Hi Burdy;
I assume that your '89 has the Solex Cisac carburettor. This dual-barrel carb has fixed jets for air/fuel-mixture, as opposed to the needle found in SU and Zenith/Pierburg 175 carbs. The jets might need cleaning though, but they do not wear. And the main valve might need replacing.

Your car should have a mechanical fuel pump. If it is failing, I would expect it to pump less, not more fuel. But the Cisac has two plastic floats which has a tendency to leak when they get old. If they fill up with fuel and sink, they will open the main valve too much and let too much fuel into the bowl.

One problem I had with mine once, was that the bolt that serves as an axle for the choke linkage came loose, causing 1) the choke flap to close and 2) the throttle linkage to lock up with the choke linkage in full throttle position (a "very interesting" experience, particularly with an automatic transmission!). You might want to check if yours is tight, if not you may experience over-fuelling. I seem to remember that the bolt took a 14 mm socket:



Good luck!

I'e had a brief look now and taken the air cleaner hood off the carb and also the top plate that has enabled me to get the floats out. They look as if they have been chewed by a dog. I can't imagine how they get like that. There seems to be an acute shortage of floats and repair kits for this carb and after a good search around the net I have managed to find what I want but at £20 for a float and £35 for a gasket kit its a lot of money. Anyway I will hopefully sort this out this week and post the results for others guidance.

Thanks Earling for your reply, my spindles are all tight.

Just rememebered. I went into the local dealers and got chating to a very helpful guy. He started the engine and at tickover he squirted all around the carb with carb cleaner from a pressure spray. The engine faltered as it drew air in from an air leak which in this case was a gasket breaking down where the carb is bolted to the inlet manifold. It would obviously show leaks elswhere on the inlet system. I have never seen this done before and thought it was a great way to trace leaks.

[Glen Morangie]

Hi,

these gaskets do go, but another common problem with the cisac is the baseplate distorts and is no longer flat. I have been told it's possible to grind them flat again, although I've never tried it - my own cisac has this problem and is currently sealed with silicone sealant - I don't know if this will last long in the hot/fuel vapour environment above the inlet manifold.

Replacement cisacs are still available from Volvo for around £650!!

(worse if you have the pierberg - these come in around £900).