Hi got a rather anoying problem with my punto, its 2002 and a 1.2 we have been to the garage several times but no sucess.
The car starts fine the first time you turn it on however if the engine gets hot or you sit around eg in traffic or waiting for someone then it wont re start for 15 mins-30 mins after i have turned engine off and it has cooled down.

any suggestions please? x

I have the same problem with my Siena 1.2el.Can pull myhair out .I you here of somethig please let me know.

Thermostat stuck closed maybe?

temperature sensor (green plug on the inlet manifold) ?

If coolant temperature sensor is telling ECU that engine is cold when hot, it may be injecting too rich a mixture. This can wet the plugs and prevent ignition (erstwhile referred to as "flooding"). In the old days, we used to clear any flooding by starting with the throttle fully open. You could try that but unlike the days of carburettors, the ECU will know that the throttle is open so trick might not work.

You could really do with getting a reader on the ECU to see what's occurring.


red

Pull a plug when it doesn't start.

If there is a spark, its a fuel problem, if there is not a spark its an ignition problem.

Report back

Cheers

SPD

my punto fires up first time every time but in sping andd summer it dosnt matter how far i go as soon as i turn off it wont go againe for at least half an hour but when weather is cold winter time their is no problem any advise please does my head in when going just to fill up with fuel and be stuck on the forcourt

Engines start fuel rich and switch to normal fuel ratio when hot.

The lambda sensor controls the fuel mixture by sensing exhaust gas oxygen. It is switched out when the engine is cold and comes into play when the engine is warm/hot.

It could be the lambda sensor giving the wrong signals or the temperature gauge sensors are not letting it switch in. The latter are cheap so change them as see what happens.

Even better get the software and cable and look at the ECU fault codes.

It could also be a multitude of faults which happen when the car is hot. As the garage have not got a clue, FiatScan and laptop cable would be a good start.

I can't believe no-one in answering the original question didn't mention the Crank (RPM) sensor.

It's a classic fault- hot engine, sensor breaks down and fails= non start. Once engine and sensor cool down, rpm sensor begins to work again.

No worries someone good has mentioned it. Fault codes would have found it (eventually)

WhiteSei said:

No worries someone good has mentioned it. Fault codes would have found it (eventually)

Click to expand...

Not always. RPM sensor doesn't always flag-up an error (ECU only knows the engine is cranking over when it sees the signal... no signal = ECU assumes you're sitting still with ignition on).

Eventually the ECU will see the MAP reading drop below atmospheric and realise the engine must be turning over and recognise an error, but it's not guaranteed. Modern stuff will see the cam signal and recognise a crank sensor fault too.

pstevo99 said:

my punto fires up first time every time but in sping andd summer it dosnt matter how far i go as soon as i turn off it wont go againe for at least half an hour but when weather is cold winter time their is no problem any advise please does my head in when going just to fill up with fuel and be stuck on the forcourt

Click to expand...

so in thick i dont know what your on about terms the car is over heating

D4nny was saying the engine crank sensor is probably faulty. Its a block of resin plastic with electronics inside that sense the engine is turning. When electronics fail they usually go dead and heat makes them more likely to fail. Hence your strange symptoms

I dont know what model yours is but they are not megabucks.
http://shop.ebay.co.uk/i.html?_nkw=punto+crank+sensor+&_cqr=true&_nkwusc=punto+crank+sensoer&_rdc=1

pstevo99 said:

so in thick i dont know what your on about terms the car is over heating

Click to expand...

I'm glad someone could understand that?

A bit of a guess - hope it helped

to me it sounds like a crank shaft sensor, these are a common fault on punto's, alot come back with the buyers complaining at work that they have a similar problem to you, i just change that sensor and it always works a treat!

I have tested with a faulty crank position sensor. Cold passing a steel object past the end of the sensor created a voltage. Put the sensor in a cup. Filled it with hot water, gave it 2 minutes for the heat to soak in and tested again. Nothing. Gave it a few minutes to cool down - started working again.

There you go and a quite handy test. Well done D4nny

I just have a couple of old, duff when hot, ones in the bottom of my toolbox for testing (one 1.2, one for a JTD).

Leave car running and wait til it cuts out, swap sensor over with cold one from toolbox, see if it starts. Damn handy. Proved a sensor fault in a Multipla when the AA and another garage had convinced the customer to pay for a new fuel pump.

Sometimes old parts have their uses.

Sensor on a 2.4 marea is only accessable from beneath and is damn difficult to get to... Think its a bit easier on a 1.9.