Tuning restarts immediately after cutting off.

[polerafon]

good afternoon all.
not going to search thread for answers, but i hope for some help.:slayer:
i have a fiat uno 1100 (95 model).
i can start the car no problem. it will idle continuosly without a miss. i have taken the car out for a 10km drive after adling for about twenty minutes and on the way back she cuts out. continuosly.
i have changed the module(ecu) changed the starter coil, serviced the alternator, bought a brand new battery, :idea: this is what happens when driving, : the battery light will come on, all the gauges will drop, then she will cut out and restart immediately without a problem. drive for 100 metres and do the same thing.

:bang::bang::bang::bang::bang:what the heck is wrong with it now.

 

[btmaldon]

It does sound very much like the crankshaft sensor. I dont know where it is on an Uno as ive not had to look for it.

These usually start playing up when the engine is warm.

All the best

 

[sdlsaginaw]

It sounds like a bad connection in a connector, fuse, or ignition switch. At first the connection works because it's cold. With current moving through it, it heats up and gets worse and worse until it starts cutting out.

Someone with schematics might be able to give pointers. Otherwise, you might look for connectors with burnt/melted plastic. Or, once it's acting up start jiggling connectors to see if you can get it to cut out. You might also be able to feel a connector that's warm due to the voltage drop.

Good luck, electrical gremlins can be a challenge. If you can't force it to occur, or feel/see something that is getting hot then schematics and a meter may be your best option.

 

[Delfos33]

!

Had the same problem on my fiorino 1.5 Spi 91 model. Changed same parts plus a fuel pump but no luck. Problem solved with a new ignition switch. Be careful on the cables as they become loose.Also, it would be wise to check crankshaft sensor for correct voltage before buying anything.

Good luck!

 

[alexGS]

No crankshaft sensor on an Uno FIRE, as far as I know. The timing is set by the breakerless pickup inside the distributor.

This does sound like the usual finned-module problem BUT the no-charge warning light coming on means there is no alternator output. The electrical system floats at some incorrect voltage that causes the ignition (and gauges) to stop working. As Delfos said, a faulty ignition switch is a likely cause of that incorrect voltage.

Check the condition and fixing of the earth strap - which is actually an earth cable that bolts to the gearbox and the metalwork under the battery. Actually take it off and wirebrush it, in case some mysterious oxide layer is providing a resistance.

Are you certain the voltage regulator or rectifier diodes in the alternator aren't faulty? You could try driving with the alternator disconnected for a while, to see whether the electrical systems play up in the same way. If not, then perhaps swap the alternator for another? I know it is frustrating when you have already rebuilt it, but it happens to us all...

-Alex

 

[sdlsaginaw]

Not likely an alternator/regulator problem as the battery would supply power in the absense of alternator power.