FUEL PUMP - BURNED WIRE AND TEMPORARY FIX

[Luca]

Hello,

 I have a 2000 450 diesel smart (city-coupe).

Today I stopped the car after a 1-hour drive and 5 minutes later the engine was not starting. The starter motor was working perfectly, but the engine was not starting.

Not hearing the noise of the fuel pump when the key is in position 1, I checked the wires in the fuse/rele'  box under the left seat (see FQ101 guide). I noticed that the fuel pump wire is kind of melted (connector H-LS I pin 2). See the pictures below.

With a 10 A fuse-protected wire from the cigarette lighter, I provided 12 V and the car could start. Then I drove home (1 hour again).

Now I've cleaned the "burned" connector and the car seems to work properly without the external 12 V. I am also going to replace the fuel filter (was not old though).

 

QUESTIONS:

- While driving back I could not disconnect the external 12 V, otherwise the engine would switch off. Is normal that the fuel pump is always active while driving?

- What do you think happened? Should I measure the Amperes that the pump uses to see if is working properly?

- Where can I buy the crimps to replace the bad ones? Do you know how to replace them?

- Does someone have the ECU pinout for the diesel version? I could only find the petrol ones on Evolution

 

Thank you.

 

 

 

[Luca]

Quote

While driving back I could not disconnect the external 12 V, otherwise the engine would switch off. Is normal that the fuel pump is always active while driving?

 

From Post #5 of this discussion seems that the pump must be always on. 

But right after it says that sometimes the pump is switched off.

Edited January 29, 2024 by Luca

[Luca]

Quote

What do you think happened? Should I measure the Amperes that the pump uses to see if is working properly?

 

Looking at some old posts seems to be a common problem for cars that have everything integrated in the SAM (newer models).

The solution seems to be the external relay. In my case, I don't know where to take the external 12 V to feed the relay. Maybe I can use pins 3 or 4 in the connector "H-LS I"  (Constant Live from the front fuse box) ?

Any help is appreciated. Thanks!