My wife's freelander i6 auto petrol has had a new alternator installed(after we stalled whilst on a summer road trip)-bit of a nightmare.The installation was completed by a dealer situated very distant from where we live.Upon receiving the car back it appears to have developed a start up problem which was not present initially.Basically it takes 2 to 3 attempts for the engine to fire.The starter,battery,alternator,etc. are all fine.No fault codes on diagnostics.It seems that the fuel is taking longer than the required 1 to 1.5 seconds to get to where it is needed in the engine.One theory is that in stripping to get to the alternator the mechanic may have damaged or not replaced a part(perhaps a non-return valve in the fuel line) so causing the delay in the uptake of the fuel and hence manifesting in the problem of repeated start ups.The car idles,drives and performs normally in all other respects.A second dealer in the city where we live cannot find the fault(at least not on on the the computer he uses to point him in the general direction of the problem).If it is a fuel line problem of the type suggested,I am told it will not record as a fault on the computer diagnosis.Will a re-strip be required to get to the problem?Have I in my layman's fashion even identified the problem correctly or am I completely off the mark.Two authorised dealers cannot pinpoint a solution so I reckon I am quite entitled to theorise a solution.What I would really appreciate however is a more technically based solution by someone in the know! Any assistance is appreciated.

Install a manometer in the fuel rail port and monitor the pressure of the fuel line after shutdown.
Also when cranking. This way you'll have an idea if it's fuel related or not.

Ok thanks a stack. Iwill convey this to the dealer as I have the car booked in for a further look at the cause.Are there any other possible explanations that come to mind?Another thing,the car seems to start first time on a cold start even though the cranking time is unduly long.As the day wears on and especially once warmed up the issue of repeat start ups manifests but generally I would have to say that it is merely the start up that is problematic;all else including idling acceleration,etc. are normal.

For the moment, I don't know what to say...
There isn't a no-return valve to tank as the system doesn't have a fuel return line.
On the end of the fuel rail is a pressure and temperature sensor.
The system regulates the pressure in the system by driving the fuel pump with a PWM type signal, based on the pressure sensor information and driving needs.
Therefore I've said to monitor the pressures in order to see if the needed fuel is there or not in all conditions.
If the pressure is low, then look for a clogged fuel filter or maybe when they put the things back some rubber line got twisted and therefore the system is having hard time to generate the proper pressure.
You should have at least about 3.8 bars (54 psi) in order for all to work out properly.

Also a problem could arise if the evaporative system isn't functioning properly. But because the hard start is also on cold startup, then this could be (with a reserve) dismissed.

Noted and thanks again.I think there is enough in your reply to start looking(and testing for) a possible fuel problem.I have an appointment with the workshop foreman in 2 days and will diplomatically suggest your test as a starting point.

Had the car at dealer for 2 days and they did all kinds of tests including fuel pressure test as well checked all the necessary sensors( fuel pressure/temp,crank,etc).They even tried to reproduce the fault so that it would reflect on the computer as a fault.No luck.They are as baffled as I am(which is cold comfort really since I am not a mechanic) and now have suggested that they will have to contact the "help desk" in UK for direction.All the diagnosis has been attempted via their computer which does not register the hard start problem,but which they agree is a problem quite evident when an attempt is made to start the vehicle.They are reluctant to do anything at all not prescribed by the computer.Is there still a place for common sense in addressing this problem outside of the realm of coputer technology and in terms of good old fashion skill? My wife has been driving a hired car for the past 2 weeks and this does not sit well.What next?

We know that on a gasoline car three things must be working properly in order for the car to function.
Air, Fuel, Spark. So what I will say is common sense...
As the fuel pressure has been checked and is OK, then:
Air: Check the electric throttle.
Fuel: Check the injectors actuation and their command.
Spark: Check the spark coils and their command.

Just spoke to the technician working on the problem and he says whilst redoing some of the tests after the car was standing for the week-end he heard a noise from the fuel tank which should not be there.So even though the pressure readings are fine they suspect a problem with the fuel pump.This it seems is inside the tank as is the fuel filter and the tank has to be removed to get the pump out for testing.Seems like a major exercise but I am desperate and cannot even contemplate an alternative.By the way forwarded your "common sense" to the technician but he says the abnormal sound in the fuel tank is pointing him in a different direction.

Hello Munier, I had a very intermittent fault on my i6 - twice in three years - when the engine ran roughly when driving. The first time I put it down to bad fuel since it cleared up when I refuelled. However, when it recurred some 18 months later on a long drive I was able to check, via the Garmin Ecoroute HD which is linked to my Garmin 1490T and gives various vehicle readings via the diagnostic port on the car, that the fuel pressure was fluctuating wildly during the rough running. The dealership replaced the pump under warranty and there has been no repeat of the problem. My recollection is that the normal diagnostic check didn't register a fault and it was because I had seen and recorded the fuel pressure changes (from between 100 and 700 if memory serves me right, the normal being around 380) that the issue was resolved quickly. It is a long procedure involving draining and removing the fuel tank to get access to the pump and having gone to all that trouble, and bearing in mind the very intermittent nature of my fault, it might be worth changing the pump rather than just checking it. I should say however that I wasn't aware of any noise from the tank, but my fault was when the car was moving at speed so I probably wouldn't have heard anything anyway.
Hope this helps, and good luck.

Thanks.All seem to point in the direction of the pump.A physical inspection revealed a clogged fuel filter and fuel pump strainer.I have authorised a replacement.Apparently the filter and pump are sold as a unit and because of the hassle in getting access down there I do not want to take the risk of replacing only a single item or even worse,merely doing a clean up.The pump assembly and filter unit together with ancillary parts is being installed and I should have the vehicle back in a day.I will do a final post after a few days driving on overall resolution.

Cannot believe it but its back to the drawing board!!Fuel pump and filter changed(a 2 day job) and the pressure is fantastic but the start up problem persists.This leaves 2 alternatives right:air and spark? In fact the technician comments that the start up problem has worsened with the better pressure. Whereas before the car would exhibit a start up problem only after standing for a while(30 min),now the problem seems to be on every start.He continues to to tinker around and my utter frusration grows.I am honestly at the stage where I am contemplating combining the principles of air, fuel and spark inside the vehicle and putting a match to the entire problem.

Quote:

This leaves 2 alternatives right:air and spark?

Not necessarily. My knowledge of modern ECU-managed petrol engines is limited, but I guess the basics haven't changed! You may have plenty of fuel pressure, but the correct amount of fuel (and air) still needs to find its way into the cylinder - i.e. the mixture must be correct. Mixture is enriched for cold starting, and if this is not happening, or the mixture is being over-enriched, this may explain problems with starting but not normal running. (It would be like trying to start an 'old-fashioned' engine without using the choke, for those old enough to remember chokes. ) In a modern engine all kinds of sensor readings may contribute to setting the mixture, but unfortunately I don't have sufficient knowledge to suggest exactly what to look for.

EDIT: I've found the following:

Quote:

The fuel rail maintains a fuel pressure of 3.8 bar (55 psi) above manifold depression under normal operating conditions, though this is programmed to rise to 4.2 bar (61 psi) in response to either:
* Cold start conditions, to improve fuel vaporization
* Cold fuel conditions, as the colder the fuel the higher viscosity

Besides Fuel, Air, Spark you do need a fourth ingredient, timing, no point having a nice healthy spark firing just after your perfect air fuel mixture disappears down the exhaust pipe. How ever you'd think something like a dodgy crank sensor would manifest itself after startup as well.

My only experience with a vehicle that would cold start but wouldn't warm start was down to a battery that had enough juice for the inital start but wouldn't recover enough if stopped too soon. Seeing as your previous problem was with the alternator has that killed your battery as well?

Munier i wrote:

the start up problem has worsened with the better pressure. Whereas before the car would exhibit a start up problem only after standing for a while(30 min),now the problem seems to be on every start.

This is just a shot in the dark, but on a "traditional" engine the symptoms you describe would either be due to an over-rich mixture or a vapour lock in the fuel line.
Now the easy way to check for an over-rich mixture was to look at the colour of the exhaust pipe - if black, mixture too rich, if grey OK, if white too weak. Commonest cause I've found (and least often diagnosed by garages) is HT leads beginning to break down. Unlikely in a fairly new engine but might be worth looking at the engine in the dark to check no blue flashes when running.
I know of no way to check for a vapour lock (although I recently watched the driver of a Ukrainian ZAZ pouring cold water on a hot carb to get the thing going again).
On a modern engine I'd have thought both of these would be picked up by the diagnostics though, so maybe I'm just blathering and not being helpful.