Technical Annoying stalling problem

[Brymak]

Hi everyone,

My Uno 60S has developed an annoying habit of not idling. Engine runs smoothly on high rev idle, but as soon as you lift off the accelerator the engine dies. This is intermittant as it only seems to get worse when the engine is at normal temp. I had a complete carb rebuild (Solex) a year ago. Could it be a sticky float chamber valve?

Thanks all. :bang:

 

[Liam]

Moved to UNO Technical to hopefully gain a quick and more informative answer.

Liam

 

[Chas Uno]

Hi everyone,

My Uno 60S has developed an annoying habit of not idling. Engine runs smoothly on high rev idle, but as soon as you lift off the accelerator the engine dies. This is intermittant as it only seems to get worse when the engine is at normal temp. I had a complete carb rebuild (Solex) a year ago. Could it be a sticky float chamber valve?

Thanks all. :bang:

This sounds like the infamous distributor vacuum diaphragm!

As yours is an 1987 60S, it should have the 1116cc non-FIRE ohc engine. I thought they had a twin choke Weber, not a Solex?

Anyway, your symptoms match that of a failed vacuum diaphragm. The idle problem gets worse when the engine reaches normal temperature, because being a carburetor engine it needs the choke out until it's warmed up. The choke also raises the idle speed (fast idle), which would help compensate for the failed diaphragm. As soon as you release the choke the idle speed drops, and with the failed vacuum diaphragm you get an air leak into the intake manifold. This upsets the air/ fuel mixture, plus also means that the advance mechanism in the distributor is not operating at low revs.

Find the vacuum pipe that runs from the distributor to the carburetor, and pull off the pipe at the carburetor. Now blow or suck into the pipe. If there is resistance (i.e. a vacuum) then the unit is fine. If there is no resistance then the unit has failed and this is most likely to be your problem.

Get yourself a Haynes or Porter manual, or look in the Uno technical threads as the changing of the diaphragm has been covered many times before. I suspect that if you replace the diaphragm (it's quite an easy job) then your idle problem will be solved.

Good luck!

Chas

 

[jjhepburn]

Could also be a blocked jet. Just take the air filter off the top of the carb and you will see the jets (look like copper screws with holes in the middle of them) carefully unscrew them, blast some carb cleaner (or brake cleaner) into them, then some compressed air (or just blow through them), and reinstall.

If this fixes the problem go buy a new fuel filter and install that to stop the problem returning.

 

[mc_wilthon]

Hi,
Possibly a bit off topic, but is it fuel injection? i had a peugeot 106 before my stilo, and it was said to have a problem with the "fuel pod." essentially, the fuel pod wasnt working properly, so at times it wouldnt be injecting the fuel into the engine without me having my foot on the accelerator telling it too. this meant when i stopped at roundabouts it would hut off. highly embarassing to be seen to stall countless times at the same junction/mcdonalds drive threw.........

 

[(CZ)enda]

I believe all carb-related causes were already covered, the only other thing I can think of is mixture too lean by carb mixture screw adjustment (but the carb can not suddenly misadjust itself ) and cut-off valve disconnected/without proper electric contact. However, I am not familiar with Solex carbs and it may be they do not have any such valve. A look at Haynes BOL instead of long clumsy description may help here.
What confused me was the "fuel pod" expression. Is it supposed to mean "fuel injection system assembly (typically consisting of injector, potentiometer and a stepper motor on Bosch Mono Jetronic SPI) located at the manifold?"