Technical 1998 Punto 1.2 8V Stalling Problem...HELP!

[jacksayorkie]

Hi

This is my first ever forum posting so please treat me gently!

I have a 1998 1.2 8v Punto which has done 56K miles. I have had it virtually from new.

The problem I’m having relates to stalling.

The Punto will run fine then will stall. Once stalled, then engine will turn over but not fire. If I then leave it for a while (originally 10 minutes but now takes 20 minutes), it fires up first time & drives as if nothing has happened… until it stalls again.

It has stalled at idle and also when driving normally (usually as I am accelerating).

It also misfires occasionally but manages not to stall, especially if the revs are above 2,500. There is obviously a temporary loss of power when this happens.

There appears to be no variation in engine temperature as the temperature gauge doesn’t do anything unusual.

I do all routine servicing myself. It had its last oil & filter change at 54K. It leaks a little oil from the top of the engine but virtually never requires topping up, so I don’t worry too much about it.

The things I’ve tried so far to cure this stalling problem are new fuel filter, air filter, & spark plugs. It still stalls. It has also had several fill ups of petrol so it’s not a dodgy batch of fuel.

There’s always a significant vacuum suction when I take the standard Punto fuel cap off. I recall an old car we had a decade or so ago (can’t remember which car) that behaved in a similar way. It turned out to be a blocked vent in the petrol cap. Could this be it? I’ve just put a temporary cap on instead of the standard one to see if there’s any difference but I’ve not tested it since putting it on.

Other possible causes: fuel pump needs changing, some problem with fuel vacuum somewhere, fuel tank vent blocked (anyone any idea how you get to this or where it is?), blocked or faulty injectors????

I’d have to have a garage do all the above jobs, I think, unless there’s some easy fix like a fuel additive to clean up the fuel system(???).

Anyone got any ideas to stop this stalling problem? I want to use the car to help my daughter learn to drive but I can’t let her drive it in this state.

Many thanks.

Jack

 

[Munkul]

as you say, your petrol tank breather (or whatever its called) may be blocked, which would account for the vacum. however, my car has the same vacum thing, and it has never stalled.
it possibly could be a dodgy fuel pump, but i wouldnt know how to check without getting a new one.

 

[jacksayorkie]

Thanks for your reply, Munkul.

Yes. I'm gravitating towards it being the fuel pump on its way out. Still open to alternative suggestions, though. According to the Haynes manual, there is a fuel tank vent pipe somewhere but it doesn't describe any way of locating it or checking to see if it's blocked.

I only did about 10 miles today with the temporary petrol cap on. Nothing untoward so far but it's too short a test to tell.

I added a double helping (one full measure to half a tank of fuel) of Redex for petrol injection engines as I was passing Halfords today. Can't do any harm. It's several years since I last put some in.

Any other ideas, please let me know.

Thanks.

Jack

 

[The Sultan]

could be a dodgy crank position sensor failing when the engine gets hot but then working when it get cold again farely common fault and fits your simptoms

the valve on the fuel tank is held shut buy a spring and opens when the vacuum gets too great so a little suction is to be exspected

other causes faulty coils as you have had it misfiring but cant see them both fail at the same time exactly causing total stopage

these are also common on mk1's

whould need someone to put an osiliscope on the crank sensor to see what it peaks at and if the signal lessens as the car warms up

 

[jacksayorkie]

That's great advice. Thanks LittlePip. Sounds like a garage job after all. At least I can go in with some idea of what to ask them to check first.

Many thanks. And yes, it does appear to be a relatively common issue. After I started my thread, I realised that others had reported similar symptoms.

Anyway, thanks again.

Jack

 

[markos]

I had the exact same problem a couple of years ago. Wouldn't start when warm, no problem when engine cold. Also it cut out a few times when driving.

As suggested already, it was the crank shaft position sensor malfunctioning when warm.

 

[jacksayorkie]

Thanks, Markos.

Anyone any idea how easy it is to replace a crank position sensor & how much they cost? Or is it best to let a garage do it?

Cheers.

Jack

 

[markos]

They are very easy to replace. If you open the bonnet and look down the side of the engine you can see the sensor right next to the flywheel (black cylindrical thing). A cable runs off the back of it and connects it to the ECU.

If you go here http://www.shop4parts.co.uk they sell them new for 20 pounds. I imagine if you go at a scrap yard or e-bay you will get a second hand one cheaper.

Of course there is the possibility that it is not the sensor at fault, but your problem sounds so similar to mine (and a few others posted in the forum) that I would bet money on it being the culprit.

 

[jacksayorkie]

Thanks, Markos.

Yes, you're spot on. I've just removed the CPS & purchased a brand new one for £28.75 (incl. VAT). Could have got a used one off eBay for a tenner but if they're a common fault, I'd rather go new than risk fitting someone else's problem.

The guy at the motor factors said they sell a lot of them so they must fail regularly. Interestingly, the sensor end of my old one was covered in oil & cack from the minor oil leak I have. That might have caused it to fail.

For anyone else reading this with a similar problem, Markos is right. Removal & fitting is an easy job. You don't even have to remove the timing belt cover. The following description might be useful.

The CPS is basically a 54 cm long wire with a rectangular connector at one end and a cylindrical sensor at the other. The connector connects to the ECU via a plug near the top of the timing belt cover. The sensor fits in a bracket at the bottom of the timing belt cover adjacent to a flywheel (which is presumably what it is measuring).

Remove the rectangular circlip holding the connectors together (I used long nosed pliers) and separate the connectors.

Extract the wire from the plastic wire conduit on the side of the timing belt cover. NB: the vertical section of this conduit has a removable panel that just clips in.

Remove the 10 mm bolt holding the sensor in its bracket. Ease the sensor cylinder out of the bracket. NB: if your sensor is covered in cack, this might take a bit of wriggling. I used molegrips to gently ease it out.

Fitting (which I am about to attempt) is the reverse of the above.

The next most important thing is to see if that's fixed the stalling problem! I'll report back in a few days time.

Thanks, once again, to everyone who's helped so far. If all goes well, you will have saved me a shedload of money that would otherwise have potentially been spent on mechanics tracking down what is an intermittent fault.

Cheers.

Jack

 

[The Sultan]

when replacing the sensor it is imperative you use some fine sand paper and some break and clutch cleaner to clean out the corrosion in the hole and on the meeting face of the braket

for 2 reasons relay first it will make it allot easier to fit and save you from forcing it causing more potential damage to the new part

secondly cleaning the adjoining face allows the sensor to be at the correct spacing from the phonic wheel if it is held out by corrosion it will pick up a poor signal

if you turn the fly wheel and look at the lumps all around it you will see one larger lump this is tdc for the engine ecu also rpm is read from it

 

[jacksayorkie]

Thanks, LittlePip.

Just got in from cricket & picked up you email. As it happens, I'd already put the sensor on my Punto this morning before you replied. Fortunately, I cleaned the bracket as best I could with kitchen roll. Not ideal, but it removed most of the cack. Certainly, I had no trouble inserting the cylindrical sensor in place and it seemed to fit snuggly and true without me having to force it.

I ran the engine for a few minutes and it was fine. However, I need to take it on a longer run to test it properly. That'll be sometime in the next few days.

I'll feed back if everything's OK so anyone following this thread can see a conclusion one way or the other.

Thanks for the info on TDC/RPM readings. I didn't know that.

Cheers.

Jack

 

[jacksayorkie]

BINGO!

Just road tested the car over 40 miles of varied driving, including long hills in high gear/low revs. Put the standard fuel cap back on to get the car back to normal trim. Engine never missed a beat!

That's the good news...

...bad news is some berk in a 4x4 ran me off the road on a deserted moorland lane. Had to take to the ditch at 30 mph to avoid a head-on collision as the 4x4 refused to move out of the middle of the road & left me a gap of under 4 foot to get through!

Car's OK apart from ripping the exhaust heat shield bracket from its mounting point. So I've now got a car that works but that rattles like an old bus! First fine day I get I'll have to put the car on stands & bodge a repair to the shield.

You win some, you lose some... At least I know the Punto's pretty good off road!

Thanks again to all those who helped solve the stalling problem.

Cheers.

Jack

 

[Munkul]

a success story! shame about the road hog though.
i hate people like that, i could go on and on about them all day :bang:

 

[jacksayorkie]

Yeah. Tell me about it. We live in a rural location with lots of narrow lanes. My wife was only commenting the other day that as local property is developed and richer people move in, so there is a noticable increase in posh cars whose owners have no concept of how to drive on narrow roads.

Anyway, heat shield is now back to being non-rattly. Four of the six mounting points were ripped away. I think nine years' worth of corrosion didn't help matters, though. All I did was unsieze the two bolts with the biggest washers and then tighten them up again with some old metal brackets wedged under the washers but overlapping the heat shield. That was after removing half an acre of heather and two dead grouse, of course. A simple but effective bodge... and a nice quiet drive!

Happy driving... till the next time...

Jack

 

[mariop1]

i think you have to change the ignition. if problem happen often with old fiat uno, cinquecento seicento e punto mark1.

 

[Munkul]

what a very useful answer, since this all happened over a year ago, and the solution was described in detail.....

 

[jacksayorkie]

Just a bit of feedback: my Punto's going strong & never missed a beat re the stalling problem since I changed the CPS, as described earlier.

YIPPEE!

(Apart from the fact that my daughter's nicked it off me so I drive a Freelander now. Wonderful cars... so long as you like to spend a lot of time working on the bits that don't work or fall off...)

Thanks, once again, for everyone's advice & help.

Jack

 

[Pud237]

Brilliant thread guys, I've got this problem on a new Punto I've just picked up and I'm gonna have a go at fixing it tomorrow. :thumbsup:

 

[Pud237]

Changed the crank sensor and it is fine, the problem has been cured.