Cold start after sitting all night
 

Slight hesitation with rumble first start in AM after sitting all night in 70 degree weather.After the first start and drive it starts immediately for rest of day.Any ideas?

Re: Cold start after sitting all night
 

Any faults?

Re: Cold start after sitting all night
 

No faults/codes

Re: Cold start after sitting all night
 

Possibly coolant leaking into a cylinder overnight from faulty head gasket?

Re: Cold start after sitting all night
 

Coolant level has stayed normal

Re: Cold start after sitting all night
 

Primary o2 sensor could be on the way out, or maybe coolant temp

Re: Cold start after sitting all night
 

Should have mentioned car only has 50,000 miles on it but maybe I'll multimeter test the sensors in any case.Thanks

Re: Cold start after sitting all night
 

Do you think a fuel pump check valve going bad could cause this?

Re: Cold start after sitting all night
 

No. I think a faulty check valve would only cause extended cranking before starting.

Re: Cold start after sitting all night
 

OK Thanks for your input