Thoughts welcome on these symptoms

[Yorkshire GOC]

As previously posted on 7th August - the hottest day of the year i broke down on the MI - losing revs and spluttering to a halt - Once engine cooled down she would start on the nail and the rev counter rock steady. Anyway after a few stop starts she was recovered BY rac.

Due to the fact she seemed to fail at temp but start ok when cool pointed towards electrics and lo and behold auto sparks found one of the yellow under bonnet relays had burnt out. However before he discovered this he ran her for an hour to replicate the event - and when it happened he said it looks like fuel starvation and is you filter OK as the pump checks out fine and sounded fine.

So after the relay being replaced i ran her for 2 hours up to fan temp and no problem then took on a near 15 mile journey no problem.

However today after being stuck in bad traffic and her cycling up to fan temp multiple times she cut out again with the same symptoms - so after couple more starts and stalls in traffic with the temp going up to 105 i left her for less than an hour and started her up and she got me home no problems - about 4-5 miles and as the car was moving, no traffic jams, the head temp never rose above 94 - so again points to a very hot engine = fuel starvation symptoms..

Some my conclusion is something is failing hot and working when cooled down with what appear to be symptoms of fuel starvation

So my questions

Am i looking at another electrical gremlin - if so anything come to mind.?

Can a fuel filter play up hot ? -dont think so

Can the injectors fail when hot ?

And as the sparks has checked the fuel pump relay and also lisstened to the pump when it replicated the fail at idle (took 60 minutes) he said the pump sounded fine.

Anybody had similar symptoms - suggestions welcome - will speak to Sparks on Monday to have another fettle.

[SD1too]

Originally Posted by Yorkshire GOC

... one of the yellow under bonnet relays had burnt out.

Which one Martin? That could be a handy clue.

Originally Posted by Yorkshire GOC

Am I looking at another electrical gremlin - if so anything come to mind.?

An ignition coil? That would take out half your cylinders wouldn't it.

Do you have access to any code reading equipment?

Simon

[Yorkshire GOC]

Hello

It was the yellow engine relay that was burnt on the pins -will look at the replacement and the relay number .

No fault codes - neither my reader or the RAC could find a code. Also at point of stall there is no apparent rough running/misfiring or discoloured exhuast - just a feel of fuel starvation - i have the FOC fitted.

Whatever it is she starts fine , gets hot (first time it happened on the hottest day of the year after 90 miles at motorway speed and today stuck in a traffic jam when she went up to fan temp 5 or 6 times before stalling- then a 30 minute colling down and she starts on the nail and rev counter rock steady but if you try to start too early she stalls again and it seems when the temp rises if you are stuck in traffic.- as long as i can keep on the move and the temp at normal levels she keeps going.

[roverbarmy]

Is your low speed fan working or does it go straight to high ?


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[roverbarmy]

Cam and crank sensors can fail when hot.

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[LeRich]

The wire for the crank sensor passes very close to the turbo and although it's shrouded, it can get toasted which then obviously affects its readings.

[Yorkshire GOC]

Originally Posted by roverbarmy

Is your low speed fan working or does it go straight to high ?


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Low speed fan is fine operates as it should.

[Yorkshire GOC]

Originally Posted by roverbarmy

Cam and crank sensors can fail when hot.

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The crank sensor has crossed my mind - but at point of stall the sensation is fuel starvation - she jugs for a while then stalls - would that happen with the crank sensor which would close e down straight away ? But the cooling down then starting and as long as the engine is at normal temp 88-94 she runs fine does point toward the crank sensor.I did try cranking when she stalled on one occasion and she did not start but the rev counter flickered which says to me the crank sensor is working - or is it a strange failing pattern?

As to the Cam sensor it only clicks in at start up so can only cause non starts - not stalling.

[Yorkshire GOC]

Originally Posted by LeRich

The wire for the crank sensor passes very close to the turbo and although it's shrouded, it can get toasted which then obviously affects its readings.

Yes- this has occurred to me as well - but the stall feels like fuel starvation - i expect the crank sensor to cut off without chugging to a halt - i suppose it could be an interuption of its data that leads to some kind of hesitation. -will have a look at the wiring .

[COLVERT]

Fit a new crank sensor.---