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Ask MB Paul Your Own Question
MB Paul
MB Paul, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3567
Experience:  Qualified Mercedes Benz Diagnostic Technician - 20+ years experience - Workshop Foreman for Mercedes
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Hola

Customer Question

hola
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

Hi Eduardo, what can I help you with.

Customer: replied 1 year ago.
Hola¡ le llego mi pregunta sobre el rele de la bomba de combustible??
Expert:  Marty replied 1 year ago.

Can you post your question in English?

Customer: replied 1 year ago.
Hello, I do not speak English, only Spanish, I'm using google translatordo you speak Spanish?Buy a car. Mercedes Benz SL(###) ###-####not start, he had no force in the fuel pump.I changed the fuel pump relay. the relay was short-circuitedI put new relay. but I have to connect mass from battery. otherwise the pump does not workthat can happen?Thank you
Expert:  Marty replied 1 year ago.

Does the fuel pump run when you turn the key to the start position?

Customer: replied 1 year ago.
but if I connect current from battery,if not connect earth from direct battery does not work
Expert:  Marty replied 1 year ago.

It sounds like you don't have power to the fuel pump relay. Can you test for power at terminal 8 and 9 in the relay connector?

Customer: replied 1 year ago.
if there is power in those pins
Expert:  Marty replied 1 year ago.

Yes I need to know if there is power at those two pins with the key on.

Customer: replied 1 year ago.
if there is current with the ignition
Expert:  Marty replied 1 year ago.

Have you tested it yet? If there is current on both of those terminals you will need to make a jumper wire and jump from terminal 8 to 7 in the connector and see if the fuel pump runs. Click on the attachment below.

Customer: replied 1 year ago.
right, with the ignition on, current flows through the two pins
Expert:  Marty replied 1 year ago.

Does the fuel pump turn on if you connect a jumper wire from terminal 8 to 7 in the connector?

Customer: replied 1 year ago.
only works directly putting land from the battery
Expert:  Marty replied 1 year ago.

Ok, but I need to know if the fuel pump works when you install the jumper wire in the relay connector. I want to make sure that the wiring is good from the relay to the fuel pump.

Customer: replied 1 year ago.
I've checked, 8 pin if you have current, pin 7 has no power
Expert:  Marty replied 1 year ago.

I want you to connect the two pins together and tell me if the fuel pump turns on.

Customer: replied 1 year ago.
Hello
If you are working the pump to do the 8 pin to 7 pin bridge
I have connected pin 9 to pin 7 and works with the ignition key.
Expert:  Marty replied 1 year ago.

Okay, that's fine. Now you need to see if you have 12 volts at terminal 12 when you are cranking the engine. I also need to know if the tachometer works when the engine is running.

Expert:  Marty replied 1 year ago.

Hi Eduardo, do you still need my help with this question?

Customer: replied 1 year ago.
Hello, sorry for the latestIn the terminal 12 no 12v when the motor is locking.The tachometer if it works when in March.Today I had to put negative direct connection from the battery to the fuel pump, otherwise wouldn't think q the land of the fuel pump has a bad contact.
Expert:  Marty replied 1 year ago.

Hi Eduardo, some of the translation is not very clear.

Did you test terminal 12 while the starter was in operation?

Is the tachometer working when the car is running?

Customer: replied 1 year ago.
the tachometer works with engine running.
In the 12 pin no power when the motor is working.
Expert:  Marty replied 1 year ago.

Hi Eduardo, we need to start over. I would like you to remove the fuel pump relay and insert a fused jumper lead from terminal 7 to 8 in the relay connector. Let me know if the fuel pump runs when you insert the wire into the relay connector. I've attached a picture below.