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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 49437
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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2007 mercedes benz s550: the fuel pump module..diagram..trunk

Customer Question

i have a 2007 mercedes benz s550, i also own a repair shop, we can not find the fuel pump module even though the diagram from the dealer shows it under the rear seat, we took the seat, the carpet and the trunk apart and still cnt find this module.....Does anyone know where this part is...once again its a 2007 new body mercedes benz s550
Submitted: 4 years ago.
Category: Mercedes
Expert:  Marty replied 4 years ago.
Chat Conversation Started
eurotec :

Hi, can you post the vin # XXXXX?


 

Customer:

wddng71x87 a040732

Customer:

u can text me at(NNN) NNN-NNNN/p>

eurotec :

Ok, click here for the replacement instructions for the pump. Let me know if it helps.

Customer:

not the fuel pump......the fuel pump module,.....fuel pump was already changed correctly

eurotec :

Not sure what you mean by a fuel pump module. Are you looking for a relay?

Customer:

no, this vehicle is equipped with a fuel pump module that sends a signal to the relay which then sends a signal to the fuel pump...we cant find the module, we know where the pump and relay are

Customer:

im stepping out, please txt me at(NNN) NNN-NNNN/p>

eurotec :

Ok, I show fuse #118 in the rear SAM to be for the pump and your fuel pump relay is also back in the rear SAM. The relay is controlled by the ME-SFI control unit. Does that sound like what you have?

eurotec :

I don't see where your car uses the N118 pump module.

Customer:

right now im clueless, we checked all fuses and relays, they all appear to be fine, we changd the pump and some times when vehicle is hot the pump wont engage, never from a cold start, starts everytime its cold, thats what weve got

eurotec :

Do you have spark when it won't start?

Customer:

nevr checked for spark but it loses all its fuel pressure, thats why were so focused in tht area

eurotec :

It sounds more like a bad crank sensor which would be much more common. You'll have no spark and no fuel pressure and no injector pulse if the sensor is bad.

eurotec :

And they can fail hot and cool down and work again.

Customer:

changed it already

eurotec :

Ok, then I think I would check for spark when it won't start. Are there any fault codes?

Customer:

no codes

eurotec :

From what I can see on my schematic your fuel pump is energized by the ME-SFI control unit by way of the relay in the rear SAM module. Have you tried jumping the relay when it won't start?

Customer:

no, i jst crank it over and over and keep turning key off and on and eventually it starts...

eurotec :

Is that no it won't start with the relay jumped or no you haven't tried. If you haven't tried jumping the relay I would do that next. If the car starts with the relay jumped you know you have a control problem from the ME but if it doesn't start, and the pump is running and you have fuel pressure, then you have more than just a pump activation problem.

eurotec :

Date: February 11, 2009

Order No.: S-B-54.21/215

Supersedes:

Group: 54

SUBJECT:
All Models Equipped with Engine M272 and M273

Engine Cannot Be Started When Engine is Hot but Will Start After Engine has Cooled

If you receive customer reports in the above model vehicles that the engine cannot be started when the engine is hot but will start after the engine has cooled and there are no Diagnostic Trouble Codes stored in the ME control unit, check the signal to the fuel pump relay from the ME Control unit (12VDC with Key in position "1" N3/10 pin 17 + and pin 4). If no signal is found, check the wiring from the ME control unit to the fuel pump relay. If the wiring checks out, it may be due to an open circuit in the ME control unit. In this case, replace the ME control unit and retest the signal to the fuel pump relay. Refer to EPCnet for applicable part number.

eurotec :

Check out the TSB.

eurotec :

If the car starts with the relay jumped I think that might be what you have going on.

eurotec :

Hi, I'm not sure if you saw my last reply. Do you still need help with this?

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