The Car.
Mercedes C220 Elegance Automatic. (Petrol) ? 1994 L Reg ? 63000 miles
Nature of Problem
1. The car?s engine cuts out at random intervals ? frequency of failure varies from 2 or 3 times in a mile (worst case) to once in several hundred miles. Usually, there will be a spate of failures - one or two within 10 miles of starting a journey and no more for the next 100 miles or so.
2. Occasionally, and again randomly, the car fails to re-start after the (hot) engine has been switched off for short periods.
History
Cutting Out. Problem was first noticed at around 56k when the engine ?missed a beat? while travelling at 70mph. There was a momentary loss of power, the rev counter dropped from 3500rpm to around 1500rpm for a split second before returning to normal. The car was driven for another 2 thousand miles or so before a similar incident occurred. This time I was accelerating through about 50mph when the engine faltered momentarily.
Since then, there have been numerous occasions when the engine has cut out at various speeds (a character building experience especially on motorways and in heavy traffic). The car has now done 63k miles and the frequency of failures is increasing all the time. When the engine fails, the car cruises to a halt (no bump start with an automatic) and after a short period the engine will re-start.
Failure to start after routinely switching off ignition. This fault has occurred randomly throughout the period of the other fault without any noticeable change in frequency.
Observations/Comments.
When trying to restart the engine after it has cut out, the engine turns over rapidly but makes no attempt to start. The car will normally start again if it is left alone for a minute or two. It appears that the engine will only start if the fuel pump can be heard to operate at the moment the ignition key is turned to the on position.
Similarly, when the car fails to start after being switched off for a short period, it only seems to restart after a short burst from the fuel pump is heard.
When the car cruises to a halt following engine failure, two warning lights illuminate; the Battery symbol and the ABS light. I have also noticed that if I turn on the ignition without starting the car, all warning lights except these two will extinguish after about 1 minute (Red Herring?).
Constant low volume electrical buzzing noise seems to be coming from overhead light/sunroof switch. (Red Herring?).
The car has been into the MB Dealership for a full download that failed to show any history of the fault. They admit that they are unlikely to trace the fault unless it manifests itself in their presence. Highly unlikely but even if it did, they would only have a window of about 2 minutes max before the fault corrects/hides itself.
The Haynes manual (and a Car Mechanics diagnostics article) makes two references to the fuel pump relay: one under the bonnet (black) marked ?kickstart? and the other in the boot (green) next to the battery. While I thought the descriptions referred to two different models, I appear to have both. Are they both fuel pump relays?? I have changed the green one to no avail.
I would be most grateful for any guidance offered.
Does anyone know of a good MB technician in the York/Hull area?
Mercedes C220 Elegance Automatic. (Petrol) ? 1994 L Reg ? 63000 miles
Nature of Problem
1. The car?s engine cuts out at random intervals ? frequency of failure varies from 2 or 3 times in a mile (worst case) to once in several hundred miles. Usually, there will be a spate of failures - one or two within 10 miles of starting a journey and no more for the next 100 miles or so.
2. Occasionally, and again randomly, the car fails to re-start after the (hot) engine has been switched off for short periods.
History
Cutting Out. Problem was first noticed at around 56k when the engine ?missed a beat? while travelling at 70mph. There was a momentary loss of power, the rev counter dropped from 3500rpm to around 1500rpm for a split second before returning to normal. The car was driven for another 2 thousand miles or so before a similar incident occurred. This time I was accelerating through about 50mph when the engine faltered momentarily.
Since then, there have been numerous occasions when the engine has cut out at various speeds (a character building experience especially on motorways and in heavy traffic). The car has now done 63k miles and the frequency of failures is increasing all the time. When the engine fails, the car cruises to a halt (no bump start with an automatic) and after a short period the engine will re-start.
Failure to start after routinely switching off ignition. This fault has occurred randomly throughout the period of the other fault without any noticeable change in frequency.
Observations/Comments.
When trying to restart the engine after it has cut out, the engine turns over rapidly but makes no attempt to start. The car will normally start again if it is left alone for a minute or two. It appears that the engine will only start if the fuel pump can be heard to operate at the moment the ignition key is turned to the on position.
Similarly, when the car fails to start after being switched off for a short period, it only seems to restart after a short burst from the fuel pump is heard.
When the car cruises to a halt following engine failure, two warning lights illuminate; the Battery symbol and the ABS light. I have also noticed that if I turn on the ignition without starting the car, all warning lights except these two will extinguish after about 1 minute (Red Herring?).
Constant low volume electrical buzzing noise seems to be coming from overhead light/sunroof switch. (Red Herring?).
The car has been into the MB Dealership for a full download that failed to show any history of the fault. They admit that they are unlikely to trace the fault unless it manifests itself in their presence. Highly unlikely but even if it did, they would only have a window of about 2 minutes max before the fault corrects/hides itself.
The Haynes manual (and a Car Mechanics diagnostics article) makes two references to the fuel pump relay: one under the bonnet (black) marked ?kickstart? and the other in the boot (green) next to the battery. While I thought the descriptions referred to two different models, I appear to have both. Are they both fuel pump relays?? I have changed the green one to no avail.
I would be most grateful for any guidance offered.
Does anyone know of a good MB technician in the York/Hull area?
