Intermittent cutting out at idle when warm
Discussion
Strange one this.
Normaly the Cerb (4.2) idles fine at 900rpm but lately after she has been running for an hour or so the idle starts to 'hunt' up and down, rhythmically dropping to 500rpm then back to 900 about twice a second. Shortly after this it refuses to idle at all and cuts out as soon as you take your foot off the throttle. Just cracking the throttle open a fraction will keep it running fine (at about 1100 rpm). Yesterday I managed to get the diagnostic software connected while this was happening, hoping it would give some hint as to the problem but everyrthing looked perfectly normal. Adaptives were hovering around -2 and +5 and throttle pot readings were synchronised and changed smoothly.
I do have a fuel tank vent issue which I have attributed this to in the past (a woosh when you take the filler cap off) but on this occasion I took the cap off and still had the same problem. HT leads were changed for new about 4 months ago and I put 2 new coils on 6 months ago. Fuel filter is 18 months old and the feul lines at the rear were changed at the same time.
Its hard to know but the cutout feels more fuel related than ignition but that is just supposition on my part.
Any thoughts, suggestions or hints would be gratefully received because it is getting to be a royal PITA!
Normaly the Cerb (4.2) idles fine at 900rpm but lately after she has been running for an hour or so the idle starts to 'hunt' up and down, rhythmically dropping to 500rpm then back to 900 about twice a second. Shortly after this it refuses to idle at all and cuts out as soon as you take your foot off the throttle. Just cracking the throttle open a fraction will keep it running fine (at about 1100 rpm). Yesterday I managed to get the diagnostic software connected while this was happening, hoping it would give some hint as to the problem but everyrthing looked perfectly normal. Adaptives were hovering around -2 and +5 and throttle pot readings were synchronised and changed smoothly.
I do have a fuel tank vent issue which I have attributed this to in the past (a woosh when you take the filler cap off) but on this occasion I took the cap off and still had the same problem. HT leads were changed for new about 4 months ago and I put 2 new coils on 6 months ago. Fuel filter is 18 months old and the feul lines at the rear were changed at the same time.
Its hard to know but the cutout feels more fuel related than ignition but that is just supposition on my part.
Any thoughts, suggestions or hints would be gratefully received because it is getting to be a royal PITA!
Edited by Tanguero on Monday 12th October 12:56
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