selwyng

Hi Guys

So on Saturday i heard a whinning/humming noise from the rear of the car. Placed my hand on the back seat and could feel a vibration. I figured its the fuel pump. The noise has stopped since.

I figured this is a warning sign and i have to change the fuel pump. I called the local MB dealership and they gave me a price of R3,169 ($360), however they informed me that on their system it shows that if im replacing a fuel pump i have to replace 2 fuel pumps, one on the left and one on the right. I cannot just replace 1 pump. Is this correct? the total price of both the pumps are R7,062 ($803)

benzmodz

I hope you changed the fuel filter too.

selwyng

The fuel filter was changed under 2 years ago at 220,000kms, im now doing 310,000kms.. will change the fuel filter again when replacing the fuel pump, but not sure if i should buy the 2 pumps...

benzmodz

Yes 2 is correct.

selwyng

Thanks benzmodz..

Do you perhaps know why should i change both the pumps and not just the malfunctioning pump? I asked the guys at MB why should i change both the pumps and there response was "According to their systems it says so"

I just like to know whats the need to change both the pumps...

edgarinho10

Reason why people get outrageous prices from the dealerships is because the replace the whole problem, not diagnose it and then find the main culprit. It saves them from you having to come back if the car happens to have something else wrong as well within the same system. It's easier on both parties except on the consumer pocket.

benzmodz

If one part fails you cant tell if it is because the left side failed or the right side failed. The left side can cause the right side to fail. You seem to think they have all the time in the world to place the tools on the car and run flow tests and then pull apart the old pump to determine the cause. So in this case the parts will be something like $5 and labour $1500.

a3 german

I allready had that problem and also in Portugal I had to replace the 2 fuel pumps.

reason is (what they told me) that the original fuel pumps dont work perfectly from factory and later they redesigned the system to work perfect..so they dont sell anymore the older fuel pumps, and just sell the new ones.

so, we (all w203 owners that have some fuel pump problems on our cars) have to buy the 2 new pumps because is not compatible 1 pump of the new system and 1 pump of the older one...

selwyng

Thanks edgarinho10, benzmodz and a3 german for the replies. Guess i will be changing both the fuel pumps.

Is it correct that the brand of fuel pumps used on the w203 is Pierburg and not Bosch?

edgarinho10

You can check through rmeuropean. They are probably the best and most efficient way to order parts online. They also list what is OEM

sammydragon3

i dont know if this the same to your 180 but im pretty sure the c230 has a pump on the right seat and the fuel sender is on the left side

selwyng

Thanks edgarinho10.. will give them a try. Hope they ship to South Africa

@ Sammydragon3- I think you are correct. I'm sure they are built the same in terms of the fuel delivery layout

selwyng

So i replaced the fuels pumps in the car. But the noise is still there.

I noticed 2 things (possibly), the first is when the vehicle temperature reading shows 90-95deg i start getting the whine/humming noise from the fuel pumps and/or when the outside temperature reaches 32deg celcius or greater i start getting these noises.

When the noise starts, it does not affect the performance of the car in any way.

Any suggestions?

sammydragon3

the fuel pump is supposed to make a buzzing noise

selwyng

Hi sammydragon3

This never happened before. And the noise is really audible. When the noise starts, a vibration can be felt on the rear seat. I dont think this normal. This happens when driving. Not on startup.

Carsy

I would take out the rear seat & see whether you can further diagnose the noise.

I wonder whether it is the diff or the exhaust system coming into contact with the body?

selwyng

Hi Carsy

I don't think its the either of those, but will give it a check.

I was thinking if it could be the fuel pump relay?

Glyn M Ruck

Sewyn. See the Wiki. Take out the back lower seat squab ~ 4 bolts under covers along the front of the seat). There are two round hatches. Under the RHS you should find the fuel pump & sender & under the LHS a level sender only. (this is normal layout reversed on some cars). You do not require to change both. With the lower seat out & the piece of padding removed & the hatch covers off you will hear very clearly if the pump is making a noise.

When last did your car have a fuel filter? On your model it is outside the tank. See Wiki for location & servicing. If the filter is clogged the pump can get noisy due to aeration/cavitation.

Good luck! These are US pictures so drivers & passenger sides are reversed from yours.













Filter

selwyng

Thanks Glyn!

I did replace both the fuel pumps couple weeks ago with pierburg pumps.

Now the noise has started again. I did not change the fuel filter when replacing the fuel pumps.

I last changed the fuel filter about 95,000kms ago.

Maybe the filter does needs replacing.

Glyn M Ruck

Just note that you only have one pump. The other unit is purely a level sensor.