W205 C200 M274 - Petrol / fuel smell inside cabin

[Sam B]

Hi

My W205 C200 with petrol engine M274 is suffering from the widely reported issue of fuel smell inside the cabin on a cold start. I am going to replace both of the low pressure fuel line rubber hoses which are the usual culprits. Mercedes part numbers are:

1. Braided fuel hose to high pressure fuel pump - A 274 070 35 00 and two hose clamps A 006 997 18 90.
2. Fuel hose near front left wheel (left when sitting inside vehicle) - A 205 470 33 03 (also substitutable with A 205 470 02 75).

Although I will not be removing the high pressure fuel pump itself, I do need to remove the shielding which covers the pump in order to gain access to the braided fuel hose (which is connected onto the high pressure pump with a hose clamp). I have removed all four T45 torx screws from the HPFP shielding including the two difficult to access ones at the back near the firewall. The shielding is now loose and moving, but still can't be fully lifted out due to two neighbouring hoses being in the way. These two hoses are circled red in the photo below (note: photos taken before T45 screws etc were removed from the shielding so you can still see them in the photos).

Please can someone help identify what the below red circled hoses near the HPFP shielding are and advise on the procedure for their removal if necessary? I have Clic / Clic-R Hose Clamp Pliers and Flexible Hose Clamp Pliers to remove the hose clamps etc.

Thanks

P.s. I am fully aware of the health and safety procedures for relieving fuel pressure from the service valve, disconnecting ground line of battery, allowing engine to cool down before working on the fuel line etc.

 

[Wombat457]

This may not be applicable to your vehicle but my 2007 E350 suffered from the same thing - fuel odours in the cabin and around the exterior of the car. This was know problem to Mercedes and the subject of a recall.

The problem was with the Fuel Pump located beneath the rear seat - in short, it leaked hence the fuel odours. Am not syaing this the issue with yours but might be something worth taking a look at. All you need to do is remove the rear seat and if what I described is the problem, it will be very obvious as there will be raw fuel sitting in the hollow of the fuel tank where the fuel pump connects to it.

 

[alexanderfoti]

The hoses circled are coolant hoses.

Your smell is likely from the low pressure line to the hp pump, they leak when cold then seal up, causing the smell

 

[Sam B]

Thanks both. I’m also pretty sure it’s the low pressure line going into the HP fuel pump as I can smell petrol there on inspection. The air circulation in the cabin then sucks in the smell from the engine bay. If I turn off the air circulation there is no petrol smell inside.

Can both of those coolant hoses be removed as is or do I need to drain off the coolant first?

 

[alexanderfoti]

Yes they can be removed if required.
You will need to drain some coolant and re-fill

 

[Sam B]

Thanks Alex much appreciated. I’ll get cracking and report back.

 

[mioba]

Have you done yet.

Fixing cars during hols is always a ball-ache incase you need extra parts

 

[Sam B]

All done and so far seems to have fixed the petrol smell. Will monitor a few more cold starts to be 100% certain. The braided low pressure hose going into the HP fuel pump was the culprit but I replaced both hoses to be on the safe side.

Here’s what the new hoses look like in case this helps anyone else in the future to diagnose a similar issue.

 

[BertyBasset]

All done and so far seems to have fixed the petrol smell. Will monitor a few more cold starts to be 100% certain. The braided low pressure hose going into the HP fuel pump was the culprit but I replaced both hoses to be on the safe side.

Here’s what the new hoses look like in case this helps anyone else in the future to diagnose a similar issue.

View attachment 87870

Hi, did replacing the hoses work ok. My wives car has developed the same problem?