Odd starting problem s55

[rooferboy1959]

If I don't start the car for a week or so on first turn of key it cranks normally then won't catch. Turn key off then back on and starts up. New battery, all spark plugs and ht leads only 6 months old. If I started it every day or so no problem. No fault codes relating to possible fuel pressure issue. One of my mates who is a mercedes mechanic suggests it might be the fuel returning to the tank. Its back at the indie mb garage at moment and they can't find it as it only does it if you leave it standing for a week or so.

 

[SL63 Mark]

Crank position sensor ? That caused a similar problem on my SL55

 

[mattkh]

Assuming it is a petrol engine, I reckon it is fuel related. Looking forward to what the garage diagnoses.

 

[SL63 Mark]

Assuming it is a petrol engine, I reckon it is fuel related. Looking forward to what the garage diagnoses.

It's an S55. They have a 5.4 litre supercharged V8 petrol engine.