'91 Mark III FIesta won't start cold (1.4 CVH)

[zoltansn]

Hello there,
I have a major problem with my Fiesta, if I leave it for 6-8 hours, so basically over night, it will not start. Bump-starting works. Sometimes leaving it on the jumpleads for 5-6 minutes also works. Towing will get the car going in a few yards. Once the car has started and stopped, it will start fine for the rest of the day. I try to start it the next morning, and it's all back to where we started.
My mechanic tried a load of things, he replaced the carb, he checked the temperature sensor attached to the carb, he checked the compression, and a whole load of things he was suggested by Ford garages and other mechanics - no success.
Anyone any ideas? Anything hidden or hiding in front of our eyes, but is just too damn obvious to be checked?
Anyone with a large and heavy hammer to reward my little blue miracle for letting me down after having spent about 2 grand on it altogether (half the car has been changed on it already)?
Many thanks in advance.
Z

[mat205125]

Did he change the autochoke with the carb?

[Zad]

I know this is obvious, but you mention it starting ok if the battery has had a boost. The battery *has* been checked? The voltage may be dropping under load and not producing enough voltage for the spark.

I had forgotten what a nightmare carb engines were in winter. Especially ones with auto chokes!

[freddytin]

Had an escort with very similar problems. turned out to be the starter motor, although the old unit would spin it over fine without drawing excessive current. Still not sure why , but it was fine for years after.

[zoltansn]

I do not know about the autochoke, but he had checked the battery. The funny thing is, that it seems to be electrical (finally he can jumpstart the car, so it seems, the starter motor needs an extra boost), but then again there is the fact, that it is only the first start every day. All the other starts during the day are fine with only the power comming from that one battery. I guess, the problem is not just one failiure, but a few things comming together. BTW... do you think, it can be the fuel? I mean, can the fuel somehow leak into the system, while the car standing in one place, and can that cause the need of extra power for firing up? If it makes any sense at all, it would explain a lot of things...