Technical Engine Dies

[NZUNO]

Hi All,

I have just come across this website and what an epic resource. Thankfully I have not had any reason to post before, but now my Uno is causing me grief.
I have an 1984 70S carb, and its problems sound similar to what others have had. Driving along on the motor way is fine, but when i slow down the engine dies! I have to wait five minutes or so and then it starts fine . Having searched the forum I found that others with this problem have put this down to a distributor fault. However, if i keep my foot on the gas (as i'm slowing down i put the clutch in) the car seems to run OK, its not until i take my foot of the gas that it seems to die. Is it possible that this is still caused by a distributor problem?

Any advice would be greatly appreciated

Cheers

 

[alexGS]

Hello! Welcome... Where in NZ are you?

The distributor would have been a good diagnosis, EXCEPT that you have a really early Uno that has a contact-breaker points distributor - assuming that no-one's upgraded it Look for a finned aluminium module on the side of the distributor - if not there, then you probably have the original points distributor.

Also, when the distributor cuts out, it usually does so at any RPM, so you have the feeling of switching off the ignition even while driving normally - accelerator position/engine speed makes no difference.

With the engine properly warm, does yours idle reasonably smoothly and at 900-1000RPM? If not, it could be a carburettor adjustment problem or a blocked idle jet. What often seems to happen is that someone takes the carburettor apart to clean/adjust it, then re-seals the carburettor body with gasket cement - this then finds its way into the jets. Sometimes the blockage will clear itself only to become stirred-up during high-speed running, and block the idle jet again when slowing down. This would explain the symptom well.

From your post, I'm assuming that it does idle OK but mysteriously dies when slowing down. I think this is most likely to be carburettor-related (possibly the fuel pump), but if it seems to be thermal in nature (the five minutes suggests this) then it could be dodgy HT ignition components (coil, leads) so really I'm not being much help. It needs someone to look at the car and assess the age/condition of these components before spending money on replacements. If you have access to a similar FIAT you can swap parts on a no-cost basis and see if there is an improvement.

Also, try to get access to a timing light and set the ignition timing to 10 degrees at idle without the infamous vacuum advance being connected (is the vacuum advance unit working - an air leak here will cause problems, as well-documented in other posts.) Incidentally, even when everything's working, it's normal on the 70 for the vacuum advance to have no effect at idle speeds (confusingly enough) because the vacuum port in the carburettor is above the throttle plate (so no vacuum at idle).

What part of NZ - if Hamilton, Te Awamutu, or Cambridge, then there are specialists close at hand

-Alex

 

[Chas Uno]

I no longer have the oldest Uno on the forum!!!

Alex's friend and now NZUno each have a '84 70S!

Welcome to the forum NZUno

Asides from what Alex has mentioned, I would have put the stalling down to two things:

1. Vacuum diaphragm on the distributor failed.
2. Winter in NZ = CARBURETOR ICING!

The symptoms sound very much like carb icing.

Does the engine gradually lose power if you keep driving it on a motorway? Any sign of a misfire developing when the symptoms occur?

Also, does the engine reach operating temperature, and does the airfilter have the metal pipe from the exhaust manifold to the airfilter unit connected and in place? If neither of this check 'yes', then icing could be the problem.

Any other advice you need please ask and we'll do out best to help. And if you have any pictures please post them up! It's always good to see pics of lil' old Unos

Chas