She doesn't want to start or idle properly

[Alex Gurr]

Well, the other week the car died on as I pulled up to a junction after a long (250 mile) run. I thought I had run out of fuel, so went off to the garage to get a can and fill her up. Even after fill up she was reluctant to start and kept cutting out at idle.

My initial thought was that I had sucked some rubbish up into the fuel filter or one of the injectors, but the car seems to run fine under load, so this doesn't make sense to me. What do you think? Is it worth a look or should I try elsewhere first?

I changed the air flow meter as per one suggestion, but this has made no difference. I am now about to take all the leads and plugs out and give them a good inspection to make sure there are no issues there, but I am struglging to think of what else to do without visiting the local garage.

Someone also mentioned something about getting crap in the carbon can, but I am not sure what this means, any ideas?

Any help would be much appreciated.

Cheers,

Alex

[griffter]

Alex Gurr said:

Someone also mentioned something about getting crap in the carbon can, but I am not sure what this means, any ideas?

It would mean the fuel tank couldn't breath properly. If the car runs OK with the fuel cap off (not recommended) this could be the cause.

Sounds more like something electrical's given up the ghost.

[GreenV8S]

If ti runs fine under load then I think you can rule out any issues to do with blocked supplies or faulty pumps. I would suspect a vacuum related problem - either an un-metered air leak into the plenum, or a faulty fuel pressure regulator, or a leaking regulator vacuum line (that's one that can cause all sorts of knock-on effects).

[350Matt]

I'd say Peter is on the right track, check every hose clip, condition of intake flexi pipe etc after the airflow meter.
Any air pulled in by the engine post meter will lean it right out and cause it to stall

Matt

[Talkwrench]

Did it run perfectly well up until the point where it cut out at the junction? i.e. did it idle smoothly and correctly, start readily (hot or cold) and pull smoothly?

[Alex Gurr]

It had been OK, but the idle had been a bit dicky before. Every now and again it would drop revs and struggle when cold and sometimes when hot it would hold 1,500rpm as an idle rather than the more usual 800rpm, but it never struggled as it does at the moment.

I did have an issue when the car overheated and I wonder whther this might have damaged one of the thermostats, which might have affected the fueling. What do you think?

Cheers,

Alex

[Talkwrench]

It is possible that a temperature sensor was damaged if it overheated but that doesnt usually manifest itself in an inability to idle when hot.
A likely bet worth checking out is the idle stepper motor at the rear of the plenum. They get clogged with carbon and become problematic. Unplug, unscrew and clean thoroughly. Just remember when youre screwing it back in that the body is plastic and soft alloy so its finger tighten then just nick it up 1/4 turn maximum - no more than that!

Edited by Talkwrench on Saturday 9th June 15:31

[Alex Gurr]

Michael,

Stupid question, but what does the stepper motor look like? Do you have a picture of one?

Cheers,

ALex

[Bluebottle]

This should help you:
Stepper cleaning

Edited by Bluebottle on Tuesday 12th June 15:53

[Talkwrench]

Thats the one!
A good clean up works wonders.

[Alex Gurr]

I just took the stepper out and gave it a quick clean. It was a little sooted up, but not too badly. A question though. How much movement should be in the plunger? Mine seemed to move less than a mm. Is this normal?

[Talkwrench]

That sounds perfectly normal. The plunger is driven by a stepper motor and cannot be moved by hand.
Did you clean out the tapered seat in the plenum where the stepper motor fits? That can collect soot too.