Loss of power problem

So this might take a little explaining but might be a problem others have had.

Not long after getting the car a few months ago (it had been stored for a long time previously) I started to have a problem with it starting to lose power. It would start to misfire and then eventually roll to a stop with the engine stilll running but unable to power it. Looking at the carb it seemed like there was fuel going in at first but this would stop at higher revs and eventually stall. I had the carb overhauled and it was ok for a bit but then started again. It was advised it could be the ignition coil so this was changed and the points cleaned and again was ok for a bit but the problem has now returned.

No garages seem to have a clue but I wondered if it sounded familiar to anyone? It only seems to happen after about 20miles when its warmed up. Could it be the exhaust causing the fuel to evaporate?

Any help much appreciated as ever. Would love to get to one of the events but will need to increase my range beyond 20miles first haha

I've had this problem, it turned out to be incorrectly routed fuel pipes.

The pipes were running along the engine rather than being clipped to the bulkhead, so after a while the engine heat was getting to the pipes and vapourising the fuel too early.

The symptoms are very similar to blocked jets, which confused me for a while.

Thanks Martin, I will have a look, I have a feeling at least one of the hoses has broken off its clip so could well be the problem!

Try driving with the fuel cap loose to see if that cures it. The UK X1/9 fuel vapour emissions control consists of a little hose off the filler neck with a snorkel ball valve that is supposed to let air in as the fuel is used, but stop vapour getting out when standing. If it gets blocked the fuel pump will build up a vacuum in the tank until the vacuum gets too strong for the pump and fuel stops flowing. It usually takes 5 to 10 minutes of driving for symptoms to appear.

The little snorkel hose is hidden in the hollow below the plastic trim piece surrounding the filler neck.

Thanks Rachael, I'll give this a go. All the hoses still appear to be in their correct place so I'll try loosening the cap. Is is easy enough to get to the snorkel bit to unblock it?

Have you checked the filter on the end of the pick up pipe?. If not its worth pulling it out and seeing what's lurking in the bottom of the tank

When I got mine it had similar symptoms and it was as Charlie said - crud on the filter. I seem to remember cutting off/removing the offending part and putting a disposable in line filter in. Some types of fuel pipes can collapse internally due to old age (not always apparent from the outside) and so worth replacing, or at the very least checking them out. It could be a combination of all of the possibles mentioned