W123 Fuel Pump

[cliveyboy8]

W123 230E 1985.

When I switch on the ignition the fuel pump is not working, no sound heard therefore will not start.

The three options are:

1. A blown fuse.
2. Faulty fuel pump relay.
3. Faulty fuel pump.

The workshop manual mentions nothing about a specific fuse. I have checked all the normal fuses and they are ok.

It states the fuel pump relay is "in a relay clip to the left of the wheel arch." The drawing looks like it has been done by someone attending pre-school and is very unclear.

Does that mean under the bonnet or near the pump at the rear of the car?

Also does anyone know what it will look like?

 

[television]

My information shows that it in the front fuse box 56,, I have known a wire to break where it comes out to the pump.

 

[cliveyboy8]

Thanks but that picture bears no resemblance to my car.

Maybe the fuel pump relay is located under the dash?

 

[television]

That is a picture of a Mercedes 123023


056

A 0015420219
RELAY
FUEL PUMP
056

A 0015422219
RELAY
FUEL PUMP
056

A 0015422219
RELAY

 

[cliveyboy8]

Thanks, I'll have another look.

 

[television]

There are more relays the same for other things

RELAY TO STEERING COLUMN JACKET TUBE CONSOLE
056

A 0015420219
RELAY
FUEL PUMP
056

A 0015422219
RELAY
FUEL PUMP
056

A 0015422219
RELAY
CARBURETOR HEATING
056

A 0015422219
RELAY
INTAKE MANIFOLD HEATING
056

A 0015422219
RELAY
ANTI-LOCK BRAKING SYSTEM
056

A 0015422219
RELAY
HEADLAMP WIPER/WASHER
056

A 0015422219
RELAY
AIR CONDITIONER
056

A 0015422219
RELAY
AUXILIARY FAN
056

A 0015422219
RELAY
ELECTRIC WINDOW REGULATOR
056

A 0015425319
RELAY
AUXILIARY FAN
059

A 0015426119
RELAY
THRUST CUTOFF
062

A 1235400950
FUSE BOX
BIPOLAR
065

A 0015450705
RELAY
FUEL PUMP CUT-OFF
065

A 0015456805
RELAY
FUEL PUMP CUT-OFF
065

A 0015450805
RELAY
FUEL PUMP CUT-OFF
065

A 0015450805
RELAY
FUEL PUMP CUT-OFF
065

A 0015456705
RELAY
FUEL PUMP CUT-OFF

 

[stwat]

Thanks but that picture bears no resemblance to my car.

Maybe the fuel pump relay is located under the dash?

That diagram shows a left hand drive vehicle, so flip the fusebox and relays to then other side and all should become clear.

 

[jaymanek]

Relay is on left side above under dash panel just above bonnet release

 

[Mikesmerc]

If it is the same setup as my W123 280CE the fuel pump only works when the starter motor is engaged, when it fires up the switch on the metering plate kicks in and continues power to the pump. To check if the pump works depress the metering plate by hand with the ignition on.
Rgds
Mike

 

[television]

I see that there are 2 relays listed, fuel pump relay and fuel shut off relay, OK we know that the fuel shut off is the one the CPC uses. Is the other one used just as a relay, the system must charge to fill the system.

 

[zrimo]

Hi there!

I'll waking up old theme. Last week I had similar problems.

1. car working normally, I was cruising around town
2. at slow acceleration from start the engine suddenly shuts down without any explanation
3. after I was trying to turn on engine again I noticed that when I turned key half through, the fuel pump wasn't making any buzz as before (before cranking engine there was always fuel pump buzz for around 2-3 seconds).
4. I checked the fuses and they're all fine
5. Later I took of fuel pump and connected it to external source of power (battery) and pump worked fine. I even tried compression test on fuel pump and it worked fine.
6. Than I installed fuel pump back in to the car and tried to start the engine. Again, pump didn't make any buzz and I still can not start the engine.
7. Fuel pump cut-off relay is looking absolutelly fine (even inside of it) to an eye. It's even making that classic "ticking" noise at start when key is in ignition position

Does anyone have any idea for sudden engine shut down and the fact that I can't hear fuel pump anymore when turning key into ignition position? Could be possible that ignition system failed to make spark? Distributor, sparkplugs etc.?

Cheers, Tim

 

[mattkh]

Does anyone have any idea for sudden engine shut down and the fact that I can't hear fuel pump anymore when turning key into ignition position? Could be possible that ignition system failed to make spark? Distributor, sparkplugs etc.?

Cheers, Tim

The system that thinks the car has rolled over, cuts the power to the fuel pump to stop the fuel catching fire.

 

[zrimo]

Good thinking, will check for that and will come back with informations. Thank you very much mattkh!

 

[zrimo]

The system that thinks the car has rolled over, cuts the power to the fuel pump to stop the fuel catching fire.

I didn't find the switch that cuts the power to the fuel pump. Anyways I did find a dry soldering on fuel pump cut-off relay. I solder it and now it's working again. Thanks for your help!

 

[mattkh]

I didn't find the switch that cuts the power to the fuel pump. Anyways I did find a dry soldering on fuel pump cut-off relay. I solder it and now it's working again. Thanks for your help!

Well done.
Very happy for you.