Hello everybody,

I need some help with the following..

My Punto (MK1, 8V, 60S) broke down a couple of days ago. The problem: engine will not start. The starter motor turns the engine but the engine just doesn't come to life.

I have breakdown assistance so I called it, but the mechanic couldn't figure out what was wrong either.

Things that have been checked (by mechanic or myself) are:

- CODE lights up and disappears (as normal)
- Injector light lights up and disappears (as normal)
- When key is turned in ignition the fuel pump can be heard working
- Starter motor turns engine
- As engine turns alternator turns as well (so not stuck as in another post)
- Full tank of fuel
- Fuel cut off switch is depressed (normal position)
- Distributor works/spark plugs work

I had a look at previous posts and some people mention RPM sensor or Lambda sensor. Could failure of either have the effect described above?

Is it possible to check if either has failed without buying replacements?

Can anybody think of something else? The mechanic mentioned possible low fuel pressure but how can I check that?

The car is quite old and I have spent a lot of money on it so I am trying to avoid another expensive garage bill..

Thanks

Mark

turn the car over for a few seconds and immediately take off the air box front and sniff
if the car is injecting it will smell strongly of fuel in here if no not atall realy

if the crank position sensor was faulty the car would not know when to spark and there fore wouldn't so that rules that out

if the car had witch it doesn't if it's mk1 a phase sensor on the cam and it was faulty it would still run
the only thing that it would do is go from sequential injection on to staged injection as in all four injectors at once instead of taking there turn this would affect fuel economy and bring on the engine light

incidently your car does not have a distributor nor points and rotor arm

it has 2 double end coils one running cylinders 1 and 4 the other running 2 and 3 both controlled buy ecu


so it's sparking so the crank sensor is working if you smell fuel that's working or if you remove the air filter box you can actually see the fuel squirting out of the single injector unless your car is multi point for example punto 75

so if fuel and spark is good next point of call is static timing is it correct has your cambelt perhaps sliped or snapped

here is a link to the timing on an 8v fire witch I assume yours is you haven't said
https://www.fiatforum.com/punto-technical/19733-photos-timing-marks-8v-f-i-r-e-engines.html

can you give a little more information is it a 55 60 75 85 or s sx elx selecta and so on

Hi Littlepip17, thanks for your reply.

I will try your suggestion about sniffing for petrol.

I edited the post with more details about the car. It is a 8V, 1,242cc, 60S model.

I checked the timing belt and it looked fine.

Cheers,

Mark

right in that case all yours has is a phonic wheel sensor(crank sensor) the car gets its top dead centre from this and rpm

another good place to check is under the little black cover held down with 2 screws at the back of your engine bay under here is the fuel injection relays and a single fuse for them I believe also the fuse to the right of your engine bay marked IGN needs checking as well

also when you turn the ignition on you should here the fuel pump running under the back seats I can on mine(i also have a punto 60s) runs for approx 5 seconds to prime the system

at the moment I'm thinking fuel pump but until you check all the fuses and have a listen I cant say for sure

.

Hi,

Sniffed for petrol and I can smell it, but I wouldn't say it is very strong..

Pump can be heard working when key is turned.

Checked fuses and they are all ok, also checked the relay and that functions as it should.

I am thinking of replacing the whole throttle body assembly. I can get one from e-bay for around 30 pounds. This inlcudes the injector, fuel pressure regulator, idle speed regulator etc. I am thinking, chances are one of these is malfunctioning hence the problem.

What do you think?

Cheers,

Mark

why guess & waste money on parts it dont need.Get a hours diagnostic done (£50-60) & put emphasis on garage to find the fault.Could well work out cheaper in long run.

Hi T14086,

I realise what you are saying is the logical approach but since the car will not start there will also be a call-out fee on top or a tow.

It is a bit of a gamble but for 30 pounds I thought it might be worth it.

Everything else has been checked, I just can't think what else it could be..

Mark

When was the last time the fuel filter was replaced? If this is clogged, it will not allow enough fuel through.

Ross

Hi,

The fuel filter was replaced about 2 months ago as it had developed a leak.

From then to now, everything was working fine..

if the injector is firing and there is fuel pressure then nothing else mounted in the throttle body can actually stop it running other things will just make it idle bad and not rev

so why don't you remove the air box from the top of the throttle body and get someone to turn the engine over wile you put your finger on the injector casing you should feel it clicking open as the internal parts move quite violently to release the precise amount of fuel

also wile your there you should be able to see the fuel spraying out of it above the throttle butterfly if neither of these are present then you need to look into why it is not injecting

possible causes

1 fuel pump may hear it running but it may have worn and not be delivering the right fuel pressure

2 faulty injector if so you wont feel anything when it fires

3 no common power to the injector one of the wires to the injector should be 5v when ignition on the other should be earthed by ecu to fire the injector when needed

4 faulty ecu but this is unlikely as your sparks plugs are still sparking

if you do find your injector is firing fuel and your spark plugs are working then you need to find why your engine isn't burning the mix

possible causes again

1 timing out

2 plug leads mixed up (but I trust you haven't moved these)

I just had a look and although there is some petrol coming out of the injector it doesn't seem much. Should I be seeing a proper squirt like a water pistol or something?

So I guess it is either the fuel pump not delivering fuel at the right pressure or a faulty injector or the fuel pressure regulator...

right well you should see a fine mist coming from the injector a dribble is no good
the fuel pressure regulator and injectors on these cars tend to be very reliable

so I would buy your self a fuel pump

there very easy to fit there is a hatch under the back seat base held down with 3 screws and under here you need to turn the large plastic ring holding the fuel pump in place

when you put a new one in make sure the seal is set right and you don't get the feed return pipes mixed up you shouldn't really i think they have arows on them

but I would try this

the hardest part is getting the big plastic ring undone you may need a gentle tap on the end of a large screwdriver to loosen and tighten it

there is a fiat tool for this but I think asking your dealer if you can borrow it may be a little cheeky

all the pumps I have changed have been hand tight so shouldn't be to much of a problem

To be sure of the fuel pump you can always test the pump pressure:-
disconnect pipe from SP injector and attach to tyre guage etc, you should get about 14lbs/si or 1 bar approx.
Other points to look at, is injector opening?, is injector getting opening pulse?.
As said earlier best not to throw parts at the car. If you want to emulate what the dealer would/should do then you will have to invest time and some cash on some basic tools.
Things that could stop injector opening are sensor out of range, check voltage from centre of map sensor, should be towards zero volts at no vacuum, if its high then faulty map, ECU could be not sending opening pulses, due to faulty MAP as said or faulty internal driver, also these injectors do fail.

hmm, a bit late for that now. Pump is on it's way..

I managed to unscrew the old one using the screwdriver and hammer approach. However once I started taking the plastic ring off I noticed some petrol started leaking out. As I wasn't sure how much would leak out if I continued, I screwed the ring back on.

One day before the breakdown I had put a full tank of fuel in the car. Does this mean I have to siphon some out before I remove the pump? When you have a full tank of petrol does the level raise all the way up to the top surface of the tank?

Since the pump is on it's way, I will change it and hope for the best. If it doesn't make any difference I will have to re-consider some of the other suggestions up to now..

you right injectors do fail on these but not halve as often as fuel pumps on cars with more than 70k most of the time

if you just unscrew the pump any excess fuel will just run over the top of the tank and onto the floor beneath so I wouldn't worry to much

the excess fuel you are getting is just the fuel contained within the pipe up to the filler a both the level of the tank maybe a couple of pints at the most

out of interest how much was your fuel pump
I got one for an uno a wile ago and cost me 80quid

I see, I will proceed with the swap-over as soon as it arrives..

Looking on the internet I found new pumps for around £90 and used ones on e-bay for around £30.

I got mine from e-bay for just under £30 incl. P&P.

lets just hope the pump you got is the right presure they are diferent depending on engine

Yes, I was aware of that. I made sure it was either from a 55 or 60 model.

just be careful when refiting the fuel pump as the the plastic nozzles where the hoses fit are brittle. just a word of warning hope it goes ok