Technical Fiat Uno starts then immediately dies

Currently reading:
Technical Fiat Uno starts then immediately dies


New member
Mar 13, 2023
Eastern Cape
I have a 1994 Fiat Uno 1.1 litre. The car starts perfectly and will idle for 2-5 seconds then dies again. During this time it will idle really well and rev really well to. But it will then sputter and die. Fuel is not the issue as the pump is new and I have rebult the carb recently, I also used a squirt bottle to fuel directly into the intake and it made no difference.

Any advice would be appreciated.
Whilst I'm new to the mechanics of the Uno (had one years ago but never got my hands dirty with a car until I bought my first classic six years ago now), if this were happening to my other car, I'd be suspecting the choke. Is it flooding the engine and causing it to cut out?

Or, does the carb have a return so the float chamber floods and then empties? Again, had a similar problem with my other classic.
Hmm I'll have a look at that. I did lean the air fuel mix all the way out to see if flooding could have been the issue but that also made no difference.
I am not sure about the choke I did not consider it as a possible fault. But when staring the car with the choke both on and off made no difference.
The car does not show any symptoms of flooding. After dying it will immediately restart again.

I do not know about the return on the carb, to be honest I don't even know what it would look like.

This is racking my brain. I have no idea what could cause this.
I’m not sure mixture would have an effect on flooding but then I don’t know what carbs the Uno has on it or how they differ to SU/Strombergs.

If there’s a float, I’d check the cut-off level. If you used a rebuild kit, were any replacement parts like-for-like? When I rebuilt the carbs on my other car, the replacement fuel valve wasn’t identical and thus flooded the carb on occasion, even though the mixture was set correctly.

On the Stromberg, when the fuel chamber floods, it overwhelms the jet and massively enriches the mixture to the point that the engine can’t burn all the wet fuel. My other car that has them then dumps a load on the road, just to make a point! I really wish it has returns to the tank!

A return would be a second fuel hose. One from the pump into the carb and one back to the tank. I’d be surprised if a flooded Uno dumped fuel on the road!

Edit: sorry, you didn’t say you’d rebuilt it! Not sure why I thought that! Must be tired.
I compared all the parts to the old ones an they looked like an exact replacement. The needles and seats where the same length and the floats the same size so the cut off level should not have changed. Another detail I probably should have added is that the car has been rebuilt about 6 months ago and during that time the car functioned perfectly.

I do have a return line but it is placed on the fuel pump it self. From the carb there are no return lines.

The only thing I can think of is if the pump was damaged some how and is letting more fuel through than it should. I don't know if that is possibility or maybe the return line of the pump got clogged and it not overwhelms the carb with fuel.
Possibly. But damaged pumps generally send less fuel to the engine.

I wonder where the fuel filter is on the carb model and whether it's on the see-through sort? Can it be seen to fill up and does it empty? A test to check it's working fine would be to disconnect it and put a hosed end into a bottle to catch the fuel. You should get a decent stream.

With the floats, can the float level be set? On the Strombergs, you can set the height at which they cut the fuel supply by bending a small metal tab. New floats on those carbs need setting using a ruler and 90º angle to read off the highest point on the float.

As another thought, our cars are old, so crud could have been sucked into the carb from the tank, although it would have to get past the filter. It's possible something could float around, block the jet and drop out once it stalls. Thus fuel starvation could be the case and not enough fuel is getting to the carb after cranking. I would surmise that the pump runs on cranking, to fill up the float bowl and get the car started but after that can't keep it running.

When you say return line on the pump, does that mean there are three hoses coming out of it? One from tank, one to tank and one to carb?*

Or, if might not be the carb at all. For example, whilst the battery might have enough oomph to start the car, if it's faulty or the alternator's not doing it's thing, it might not be generating enough electricity to keep the engine running (how fast is the starter motor? is it slower than it used to be?). Alternatively, it could be a vacuum leak at the manifold, which would cause lean running and thus cause it to cut out.

Sorry if this sounds like clutching at straws. How Unos work is new to me at the moment!

*Been reading up on the layout of the carb Uno and it does! Wow, that's interesting!
Last edited:
After starting can you run continuously with some throttle? If so then I guess you are looking at an idle only problem.

Next is check to see if you have an idle / overrun cutoff solenoid. This will look like a small round canister with one or more wires screwed into the lower area of the carb body. Its purpose is to shut off fuel delivery on engine overrun conditions. Maybe this is being energised when it should not be. I can't recall which way the valve operates with respect to voltage. i.e. closed with 12V or closed with 0V.
My old panda MK1 4x4, 999cc carb, did exactly that and it was a coil that was breaking down (and an X19 of mine)…I only found it by chance on resting my forearm on it whilst ‘carb-fiddling’ and it was hot to the extent my skin blistered up…I don’t mean just ‘hot’, I mean seriously hot, enough to start a fire. A new coil worked wonders, although I did swap it out it for the later dizzy coil pack set up