(G) Uno 70sl Stall.....

I need help with my Uno 70 sl 1989
The engine won't start sudenly. Battery is Ok, Motor Starter work Ok, Carb is cleaned and good, the sparkplug is new also the Coil, CDI and Magnet at distributor is new too, But it still won't start/run.
The cylinder compression is 8 bar, is that high enaugh ?
Thanks.....

I had some compression problems earlier on my Uno, but if all cylinders show the same reading, they are ok. Mine read 8,8,12,12. There was an air leak between those with lowest reading. Blown head gasket, and no start!

Morten.

CDI? I presume you mean the finned box on the side of the distributor. Scooters have CDI... :-)

Does the engine sound 'normal' when cranking over? If it makes an uneven stirring sound you need to first look inside the oil filler with a torch, to make sure the camshaft is turning (need I say more... :-)

If the cranking sound is uneven but cam is turning, then suspect blown head gasket as Morty describes.

If engine sounds normal you have, presumably, removed a spark plug and had an assistant hold it against engine with insulated pliers... check for spark while cranking.

If spark is OK then you need to see if plugs are getting wet after prolonged cranking with choke, multiple stamps on accelerator, etc. If no sign of petrol then take the air cleaner off and watch carburettor barrel while you operate throttle linkage. Should be a strong squirt of petrol. No squirt suggests that carburettor may be empty - suspect fuel pump. Take off fuel cap to ensure no vacuum in tank.

Recently when I tried to start up my Uno after head gasket replacement, I had a major problem with flooding. Symptoms were that everything seemed perfect but engine just wouldn't start. Solution was to hold accelerator all the way down, and keep cranking until started.

I had an Uno 70SL a few years ago that sometimes wouldn't start unless the accelerator was held down as above to 'dry it out'. The problem was eventually traced to the inlet manifold gaskets leaking water into the cylinders. A pleasant discovery because it was much simpler to fix than a head gasket!

-Alex

Yes.. that what I call CDI ...
yes there is spark on the plug when I crank the engine, the gasoline squirt too. But there is no response when I adjust the timing advance from distributor while I crank The engine, It seems like no Fire/spark.
BTW what is the correct / standart compression for Uno 70 Sl ?
Thanks guys....

I have no clue about the exact standard. But it's most likely to be around 12. But after many years of wearing and tearing (eyh! that's a Led Zeppelin song isn't it?) it falls, so 8 isn't a problem if all cylinders show the equal pressure.

CDI = Capacitor Discharge Ignition. Any electronic ignition system uses this principle, so definitely in the case of the carburetor Uno's with electronic ignition the finned box on the side of the distributor is in fact a CDI system. Not so sure about systems with fuel injection, though suspect they are the same only controlled by an ECU rather than by the distributor.

Tech talk over!

Not all electronic ignition uses the CDI principle. The idea of CDI was to build up voltage in capacitors, which then discharged rapidly to fire the coil with dangerously high primary voltages, generating higher voltages to the plugs. Many years ago there existed CDI boxes that would hook on to a standard points ignition system and provide more energy to the standard coil. The idea was that since contact breaker points are only closed for a short time, the capacitors allowed more energy to be stored during this time.

The finned box in the Uno system does not contain any capacitors. It serves more to amplify the weak AC voltage from the reluctor pickup, and switches the coil on and off by means of transistors. A better name for it therefore is 'ignition amplifier' or 'igniter module'. The coil itself is redesigned to provide more energy. You can prove that it is not CDI if you measure the voltage across the coil - only 12V.

CDI is confined to single-cylinder engines these days due to cross-firing problems. A quick Google search shows that it is used mainly for motorcycles. There is very little about the use of CDI on cars, but here is a brief mention: http://users.mrbean.net.au/~rover/electron.htm

-Alex

Hey Alex,

Ok, I got that wrong then! Whoops! I go to the back of the class with the dunces hat on....!

I assumed that any electronic ignition system used the CDI principle. And you are right, the finned box is often called the 'ignition amplifier'.

And yes, my first motorbike (a 1981 Honda H100, single cylinder two stroke engine) used a CDI system. I thought all electronic ignition systems used the same principle.

Show how one shouldn't use the power of assumption!

Thanks for the info and helping us all understand the inner workings of the Uno better.

Chas

Chas,
I have to admit that you are in quite good company after my Google search - there are a number of people out there that believe in all electronic ignition systems being CDI, maybe because CDI is often the only type of electronic ignition that people have to work on (!), either because of it's aftermarket fitting to old cars, or because of the strangely high failure rates in motorcycles.

So I hoped you wouldn't take it personally... and thanks for the kind reply.

Meanwhile those Uno 'finned boxes' are not terrifically reliable - I've had problems where the ignition timing was varying mysteriously by about 5-10 degrees - enough to 'randomly' upset the idle (and my temper!) I have tried to replace them with an electronic ignition kit working off the original pickup, but that was even more ridiculous (the timing would RETARD as the engine speeded up) so I went back to points - easier.

I think the best you can do is to reduce the air gap of the pickup so that you can feel 'pulses' as you turn the distributor, and also re-insulate the pickup wires if necessary (they are either in fine condition, or they are falling apart!)

-Alex

Yooooo... Guys... My UNO start....
He...he...he...he...ha...ha...ha..
Guys.. I finally solve the problem... It finally start now.... The fault is at the distributor cap. Mine is worn, the carbon tip inside the distributor cap was crack and only a half size left there... hi ... hi ... hi... so I change with a new Distributor cap. And you know what happened ...? It start... the engine run.... Now I can take my Uno back to street again....
Thanks a lot guys... Morten, Alex, Chas ... and everybody....

Hey.. Alex, look like you have workshop / garage there.... U are expert on these. am I right ?

---- UNO FOREVER MAN --------

Jemmy,
Sorry that I was actually no help at all with your problem... I was guessing around a bit while we were thinking of more severe problems: "If spark is OK then you need..."

Then of course there was the little discussion about CDI and what it wasn't, which was absolutely no help to you ;-)

So really I think we can all learn from your own diagnosis and check our distributor caps first before fearing worse problems...

I think that answers your second question of 'am I an expert' - no way! I am not trained as a mechanic, though I think I am pretty good (doesn't everyone...) You have to consider each problem on its own merits and compared with past experience. Having owned a number of FIATs:
1974 128SL
1986 Uno 45
1988 Uno 70SL
1982 126 Personal 4
1986 Uno 60
1989 Tipo DGT
1988 Croma i.e.
1988 Uno Turbo i.e. -still have this
1981 X1/9
1988 X1/9 -and this
1987 Uno 60 -and this
plus a Lancia Thema and an Alfa 164 (current 'best car'), I have had a bit of experience (including a number of mistakes!), but there is always room for plenty more at the 'Alex Garage'!

Thanks,
-Alex