325i Sport trouble starting from cold.........

[j555boy]

Hi,

I have a 325i sport with a starting problem. From cold you turn the key and it turns over for about 5-10 seconds and nearly starts. Then I turn it again and it starts immediately.

When hot it always starts straight away.

Any ideas? Looks like a new blue sensor has already been replaced, but it could be a dodgy one I suppose.

Thanks in advance.

[Brianmoooore]

Sounds like lack of fuel pressure, caused by a leaking injector, fuel pressure regulator, non return valve in the fuel pump, or rubber fuel hose.
A leaking injector will make it even more difficult to start by making the mixture too rich, before the excess fuel in the manifold is burnt off.

[j555boy]

Saying that I do hear a humming/vibrating noise from the fuel pump area under the seat once I turn the car off.

Fuel pump you reckon?

[Brianmoooore]

Fuel pump is supposed to hum, but not after the engine is switched off.
You need to tee a fuel pressure gauge into the supply pipe to the fuel rail, and see what's happening. You can buy a cheap one for about £10, and will need a short length of 8mm fuel hose to go with it.

[j555boy]

Thanks Brain in the end it was the fuel pump. All sorted now.

[j555boy]

Thanks Brian in the end it was the fuel pump. All sorted now.