[tomav]

Hello all! I have an 02 ML320 which stalled while driving and now will not start. Although it was changed recently I replaced the CPS. Still no luck, I have also replaced the ignition switch as it seemed to be sticking in the start position. There is no fuel pressure and the pump will not cycle. I do not get a start error. I have tried a jumper direct to the green wire on the connector in the left wheel well and it will turn the pump on and run for a second and then die.I have tried a jumper at the K3 relay, I get power to the fuel pump fuse but nothing at the pump or connector. I can not seem to trace the wire from the Fuse to the fuel pump.Does anyone know of anything else between the two that could cause this? Also when I try to start The Fuel pump relay does not engage (no signal from ECM?) From my wiring diagram i do not see anything between the fuse and the pump except 1 connector. Any help would be greatly appreciated.

 

[art_arev]

How do you know there is no fuel pressure? Have you measured it with a fuel pressure gauge?

 

[tomav]

Pressure gauge, no pressure. Pump does not activate

 

[43sqd]

There is some confusion in your post. Please answer the following questions individually.

1. post the diagram that you are referring to.

2. where is the K3 relay that you are referring to, under the hood or the right side panel fuse/relay box?

3. what fuse # are you referring to and where is it located?

 

[tomav]

Thanks 43sqd for the reply!
I am using the following wiring diagram Pg 76 fuel pump:
http://bayhas.com/w163manu/Repairs/wiring.pdf

The relay location is under the hood left side K3 just above the horn relay, mounted above the AAM module.

The fuse #38 is just above the K3 relay on the left side of the fuse box:
http://www.benzworld.org/forums/attachments/w163-m-class/581026d1380270443-ml320-not-starting-even-new-fuel-k3-relay.jpg

 

[43sqd]

Thanks 43sqd for the reply!
I am using the following wiring diagram Pg 76 fuel pump:
http://bayhas.com/w163manu/Repairs/wiring.pdf

The relay location is under the hood left side K3 just above the horn relay, mounted above the AAM module.

The fuse #38 is just above the K3 relay on the left side of the fuse box:
http://www.benzworld.org/forums/attachments/w163-m-class/581026d1380270443-ml320-not-starting-even-new-fuel-k3-relay.jpg

You have a 2002 ML320 and you are using diagrams for a 2001 model. Many things are completely different between the years.

I have a 2002 ML320 and look where it indicates that relay K3 and fuse #38 are for a diesel engine only. Those two items should not even be there, unless you added them yourself.

The correct relay, K2 and fuse #13 are located in the right side kick panel fuse/relay box.

 

[tomav]

Thank you again, I could not understand why jumping the relay under the hood did not supply power to the pump.
I swapped the k2 relay and checked the fuse #13 and do have power. I still do not get power to the pump.
Do you know of any other connectors between f13 and the fuel pump connector behind the left rear tire?

 

[Noodles]

Only the connectors on the top of the pump.

 

[43sqd]

Thank you again, I could not understand why jumping the relay under the hood did not supply power to the pump.
I swapped the k2 relay and checked the fuse #13 and do have power. I still do not get power to the pump.
Do you know of any other connectors between f13 and the fuel pump connector behind the left rear tire?

If there is a K3 relay and fuse #38 in place under the hood, remove them. Were they in place already or did you add them?

You do not say how you checked fuse #13 for power. Fuse #13 will only become live as you are cranking the engine.

Start at the pump (M3/3):

1. first check the BRN wire for GROUND.

2. then have someone crank the eng. while you test the GREEN wire for voltage.

a. if there is voltage at the GREEN wire then the pump is dead.

b. if there is no voltage then there is a wiring problem and now you have to check backwards.

3. then go to connector X18/3 and perform the same test at the GREEN and BROWN wires.

4. then move to connector X18 and check for voltage at the GREEN wire a position A3.

Post back with results.

 

[tomav]

The K3 relay under the hood was already in place
I have again tested and confirmed power at the K2 relay and Fuse 13. I jumped out the K2 relay, still no power at the X18/3, I have located the X18 connector but it has a different configuration than the pin-out you supplied. I disassembled the connector and still do not have power to any of the green wires. would the next logical step be remove the auxiliary fuse panel?
I have included pictures of my X18 connector.

 

[tomav]

After tracing the wires backwards from the aux fuse panel, I believe x18 is actually above the fuse panel. I have found a broken wire just behind connector x18/3 at the left rear wheel where the wiring harness goes through the rearward frame connector. I repaired the wiring and all is back to normal.
Thanks 43sqd for all the help.

 

[Noodles]

Nice job and thank you for posting your fix. It is posting results like this that really help make our forum helpful to other owners.
Glads it is fixed and you are on the road again.

Imagine what a dealer would have charged to get this fixed. I would guess at least several hundred dollars to over one thousand.

 

[RJV]

Imagine what a dealer would have charged to get this fixed. I would guess at least several hundred dollars to over one thousand.

..... plus the connector, "shop consumables", environmental charge, etc. ya de ya de ya