Petrol smell coming from engine bay after starting up

[Murt97]

Hi guys, I just bought a 318i cabriolet... I've been noticing the smell of petrol at idle and during driving, I can't seen any visible leaking. The owner had told me that the car had not been used for over 3 months prior to my recent test drive.

Anyone got any ideas of what the problem might be?

[paultv]

Trace both rubber fuel lines from the left side inner wing where they attach to the metal feed and return pipes to the FPR and fuel rail - check for wet hoses - meaning perished rubber.

Check the FPR hose to the inlet manifold - pull it off at one end and see if it contains petrol - if it does the diaphram in the FPR is rotted.

Check around the injectors for any leaking O rings..

Check under the rear seat, remove the fuel pump cover and check the expansion tank hose is correctly fitted to the top of the tank.

Have a general snoop under the car and trace the metal hardlines back to the fuel filter looking for leaks around the tank rubber hoses.

I'm sure there will be others with their advice.

Paul

[Brianmoooore]

Trace both rubber fuel lines from the left side inner wing where they attach to the metal feed and return pipes to the FPR and fuel rail - check for wet hoses - meaning perished rubber.

Check the FPR hose to the inlet manifold - pull it off at on end and see if it contains petrol - if it does the diaphram in the FPR is rotted.

Check around the injectors for any leaking O rings..

Check under the rear seat, remove the fuel pump cover and check the expansion tank hose is correctly fitted to the top of the tank.

Have a general snoop under the car and trace the metal hardlines back to the fuel filter looking for leaks around the tank rubber hoses.

I'm sure there will be others with their advice.

Paul

This covers most of the initial checks. The M40 engine has a couple of short rubber fuel hoses, semi hidden, near the engine, that like to fail as a result of the warm environment they live in.

[Murt97]

Thanks Paul, I'll investigate in the morning...

Trace both rubber fuel lines from the left side inner wing where they attach to the metal feed and return pipes to the FPR and fuel rail - check for wet hoses - meaning perished rubber.

Check the FPR hose to the inlet manifold - pull it off at on end and see if it contains petrol - if it does the diaphram in the FPR is rotted.

Check around the injectors for any leaking O rings..

Check under the rear seat, remove the fuel pump cover and check the expansion tank hose is correctly fitted to the top of the tank.

Have a general snoop under the car and trace the metal hardlines back to the fuel filter looking for leaks around the tank rubber hoses.

I'm sure there will be others with their advice.

Paul

[Brianmoooore]

That looks like the hose in the area I referred to. If you remove the six nuts and two bolts visible in your pic. on the top of the inlet manifold, the whole top half of the manifold can be lifted away for access.

[Murt97]

Found something leaking beneath the main engine components. I’m not very techcincal when it comes to this sort of thing so could anyone help troubleshoot?

[Murt97]

Trace both rubber fuel lines from the left side inner wing where they attach to the metal feed and return pipes to the FPR and fuel rail - check for wet hoses - meaning perished rubber.

Check the FPR hose to the inlet manifold - pull it off at on end and see if it contains petrol - if it does the diaphram in the FPR is rotted.

Check around the injectors for any leaking O rings..

Check under the rear seat, remove the fuel pump cover and check the expansion tank hose is correctly fitted to the top of the tank.

Have a general snoop under the car and trace the metal hardlines back to the fuel filter looking for leaks around the tank rubber hoses.

I'm sure there will be others with their advice.

Paul

This covers most of the initial checks. The M40 engine has a couple of short rubber fuel hoses, semi hidden, near the engine, that like to fail as a result of the warm environment they live in.

So I think these are the two hoses you’re talking about..?

[Brianmoooore]

That looks like the hose in the area I referred to. If you remove the six nuts and two bolts visible in your pic. on the top of the inlet manifold, the whole top half of the manifold can be lifted away for access.

[Brianmoooore]

The two hoses circled in your 1st pic. in your 10.24am post are the two main fuel hoses. These connect to shorter rubber hoses hidden under the manifold. These are the one likely to be leaking.
Hose circled in your last pic. are coolant hoses.

[Murt97]

That looks like the hose in the area I referred to. If you remove the six nuts and two bolts visible in your pic. on the top of the inlet manifold, the whole top half of the manifold can be lifted away for access.

Cheers Brian! Do you know the exact part number for these?

[Brianmoooore]

They're just short pieces of ordinary 13mm x 8mm high pressure fuel hose available from many places. Have a close look at the two long main hoses, bending them and looking for cracks. If they are past their best, buy enough to renew the lot.
Be careful with the gaskets between the two inlet manifold halves and ensure they go back in the same position as they were. They are usually reusable.

[Murt97]

They're just short pieces of ordinary 13mm x 8mm high pressure fuel hose available from many places. Have a close look at the two long main hoses, bending them and looking for cracks. If they are past their best, buy enough to renew the lot.
Be careful with the gaskets between the two inlet manifold halves and ensure they go back in the same position as they were. They are usually reusable.

They're just short pieces of ordinary 13mm x 8mm high pressure fuel hose available from many places. Have a close look at the two long main hoses, bending them and looking for cracks. If they are past their best, buy enough to renew the lot.
Be careful with the gaskets between the two inlet manifold halves and ensure they go back in the same position as they were. They are usually reusable.

Hi Brian, I’ve had a look inside after partially remove the manifold...

Not too sure where the issue is so I’ve taken some pics...

[Murt97]

Also I have taken apart the the manifold and some of fuel lines without depressurising the fuel system... I know it’s too late but will that be a problem?

[Brianmoooore]

The fuel system has depressurised itself via the leak. Even if it wasn't leaking,m no harm would have been done, other than you would have petrol initially squirting out at 40+ PSI, which isn't ideal.
What you should have done is cranked the engine, or bypassed the fuel pump relay, before you took any of the fuel system apart, so that you could have seen the exact source of the leak.
The short (about 2" long) piece near the back of the engine is the most likely suspect, but now that you're in there, you should change the similar length piece, near the front of the engine, that goes to the fuel pressure regulator.

[Murt97]

The fuel system has depressurised itself via the leak. Even if it wasn't leaking,m no harm would have been done, other than you would have petrol initially squirting out at 40+ PSI, which isn't ideal.
What you should have done is cranked the engine, or bypassed the fuel pump relay, before you took any of the fuel system apart, so that you could have seen the exact source of the leak.
The short (about 2" long) piece near the back of the engine is the most likely suspect, but now that you're in there, you should change the similar length piece, near the front of the engine, that goes to the fuel pressure regulator.

Great info Brian! I believe this is the part you are referring to...

[Brianmoooore]

Yes, 50mm of ordinary 13mm x 8mm fuel hose. BMW's original hose clips are stainless steel and are reusable, provided you don't over tighten them and strip the thread.