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Q: Mercedes Diesel takes 30 to 40 sec to start every time cold or hot

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its a ml 270 with a 5 cylinder diesel engine.my car has hard start all the time.could it be something like the loss of high pressure from the common rail?

My car has 160000 miles.
My car has an automatic transmission.

You could be right about the fuel pressure. The system is supposed to maintain a certain amount of pressure while it is off and if that pressure falls off it may take some time for it to build up again. But it could also be any number of other faults. You didn’t say whether there is a check engine or other warning light, but I’m betting that your ECU has stored some fault codes that could lead to the diagnosis. If you contact Your Mechanic they can send a technician to your home or office who can check out your starting problem and let you know what needs to be done.

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