something badly wrong???

my very reliable 1984 R4 has become a bit of a nightmare. To pass its MOT last month the garage adjusted the carburettor for emissions.... since then it's not been running well at all and started breaking down on me. Had to be rescued a couple of times and the garage took it back (twice) to re adjust carb and changed distributor cap, adjusted points ,new sparks etc. But in the end they thought it was carburettor fault/ blockage.
it ran great for a few weeks but now it does this:
starts great, runs beautifully for 5 minutes and then slutters, loses power and grinds to a halt. With a lots of patience i can get it going again, usually takes a few minutes but it often breaks down again. Yet, after a few of these 'episodes' it drives really well. However, in central London rushhour this is too nerve racking for me and I am now too scared to go anywhere with it, don't want to go back to the garage as i feel they messed it up in the first place, and the RAC said they won't come out for me again.

So, what can it be??? and can I fix it??

Hi, did the garage actually clean the carb out? I had a similar problem on a road trip with a mk11 golf and it went away once I cleaned the carb bowl and blew through the jets.

ditto for us with the Green Pig, once the carb had had all it's components been blown through with the compressor a measure of tranquillity returned. Prior to that it had treated us to a couple of 8km treks home in the wee small hours.

good luck

Couple of possibilities - might be a fuel blockage as others have suggested. One check for this is to see if it runs when the choke is pulled out. That would mean the main jet in the carburettor is blocking. Cleaning out the carb including the gauxe on the entry pipe as others have suggested then fitting and renewing/fitting the fuel filter should fix. The gauze filter in the tank can also block. Removing the fuel pipe from the carb and blowing through it is a temporary fix.

Another thought - I had a rotor arm fail and it gave very similar symptoms. Would be fine for 10 minutes then the car would start spluttering and grind to a halt. New rotor arm is a cheap way to check for this.

It could also be the ignition coil. When they are on the way out, they will cause the engine to cut out once they warm up. After cooling down , they work again for a while etc. etc. The best way to check that is to replace with a known good one.

Thanks all for your advice
well, it looks like I will have to take a look at the carburetta. i am sure they cleaned it out last time it broke down and cleared all the jets etc.....
My car also seems to have a seperate fuelfilter....shoud i remove that?

Just a couple more question; if it is the carb why would it stop once the engine has been running for a few minutes? flooded?? wrong mixture???
it starts with choke.....

And, as a final solution, if i can't fix it, could i buy a new - reconditioned one or is that the lazy way??

Definitely remove the filter and check that the fuel lines aren't blocked. If either filter or lines are partially blocked, that could well lead to the symptoms you describe.

I think of fuel line blockage,too. Renew filter if not done yet and check the gauze filter in the carburettor fuel inlet pipe (remove it with a 12mm spanner and you will find a small filter inside). Other point, as Malcolm advised is the gauze filter in the tank pick-up tube, it clogs often but it cannot be practically checked unless the tank is removed.
Have you checked if it occurs due to fuel starvation, or flooding? Don't overlook the second factor, it can happen!

I had exactly the same symptoms and it was the condenser..Classic sign is new points pit very quickly.As fas as I'm aware coils stop working completely when they go.

Thanks all. After many battles with the carb, and me stupidly messing up the thread on the brass fuel filter screw, it turned out to be the condenser after all. But now the electrics are playing up..... if I put heater or headlights on, and want to use indicator, mad scruntching noise and lights/ indicators going ballistic. Could this be the voltage regulator???

Well done iancr900! I've never had a condenser fail, so it's good to know the symptoms. Thanks for getting back to us Mathiszig. I might have an idea about the electical problem, but will answer in your other thread.

diaphram

I had the same trouble with mine and it turned out ot be the diaphram on the petrol pump that had a slight hole in it, I replaced the diaphram filter and hey presto no problem afterwards.
Hope this helps
billythefish