Technical Uno cutting out

[killfr0g]

ok so here's my weird problem.

Just last week I had my Uno 45's carb cleaned and the fuel/air mixture set accordingly by a mechanic who specializes in this stuff. I did it because of 2 main problems:

1) when the engine was just started and cold, i used to press the accelerator and had an RPM drop and it would kinda halt on acceleration. It seems much better now, although still needs choke to run smoothly when cold, but that's acceptable

2) this problem didn't go away. My engine idles around 1000.. any less and it starts to shake and cuts off. But 1000 seems ok. However, when I stop for like 30secs or more, the engine will simply cut out. No stuttering or shaking, it just cuts out. Funny thing is, I have to leave it "cool down" for like 2 mins or so before I try to start it again, else it simply won't start!

But if I turn off the engine myself, and then turn it back on, it fires up instantly like it should. But not when it cuts out by itself!

Im grateful for any tips! Thanks

 

[jjhepburn]

It could be the vacuum advance thing on the side of the distributor, they are notorious for failing. It effects the idling of the car.

You can test it by removing the other end of the pipe (off the carb) and trying to suck on it (clean it first) if there is no resistance then the module is stuffed and needs replacing. Another way to test it is to have the car running and remove the pipe off the module, if you don’t notice any difference in the running of the car then the module is stuffed.

When the car cuts out it could flood itself (which would make it hard to start). That said though, if when you try starting the car it feels like it has a flat battery, then that means its too advanced and is firing against itself (this could also have something to do with the vacuum module) very embarrassing at traffic lights

 

[(CZ)enda]

The 30 secs you mentioned seems very much like the time for which the engine can run on the fuel inside the carb's float chamber. When it runs out of the fuel, it just dies without stuttering.
Try checking the fuel filter, possibly fuel pump.
Also, something similar happened to me when I forgot to remove masking tape I put on the fuel filler cap when spraying the area around. As it was closed airtight, the fuel pump could not suck the fuel sufficiently as it had to fight with the vacuum in the tank. After the engine died, I had to wait a minute for the vacuum relief, drove on for a few minutes, then it died again etc. etc.
Maybe it is also good idea to check the electric connection of the solenoid valve on the front side of the carb (white/red or white/brown wire, if memory serves right) although when the cable is disconnected/bad contact there, the engine will die instead of idling - which does not seem to be your case....

 

[alexGS]

jjhepburn forgot the notorious Electronic module on the side of the distributor - I replaced it on one of his Unos and at last the cutting out problem was solved. As you described, the engine would often restart straight away, but other times seemed to need cooling off.

So, try swapping the electronic module for one you know that works.

-Alex