Where is the fuel pump relay in my W124?

[ducati]

In my 300CE 1992 there are no relays behind the battery - the ECUs are close together with no space for a relay and I have looked at another CE and the relays are clearly visible. Where on earth would they hide these things???

Any help or even guesses gratefully recieved as I'm at my wits end!

 

[bundy]

hi ducati
the fuel pump relay IS behind the battery under the plastic cover.
you will see 2 ecu,s an ovp relay just to the left of these is your pump relay.
it should be marked on top with the words 6 zyl and 6zyl + kickdown if auto.
hope this helps

 

[ducati]

Many thanks but....
I've got the battery, behind this are 2 ecu, to the right is the vpo with the 10amp fuse on top, to the left is something the size of a fag packet with MAS written on the top plus a knob with arrows to o and 1
The part I've bought (as recommended on this site, the merc garage and some guy on e bay is part no 0035452405 a smaller black box with about 10 pins underneath and the part number on top...what is going on...no 6 zyl anywhere????

 

[ducati]

I should have said it is a 24V, been onto MB again and there are different relays to the 12V cars - the fuel pump relay is the box to the left of the battery with the screw down knob on top (so they say!) - I'll order a new one and let you know what happens!!

Thanks again

 

[ducati]

Oh bother!........after replacing the VERY expensive fuel pump relay/control unit (the 24v costs twice as much as the 12V) the problem is still there - back to square one!

 

[television]

Oh bother!........after replacing the VERY expensive fuel pump relay/control unit (the 24v costs twice as much as the 12V) the problem is still there - back to square one!

Is there a 24 volt version, news to me, what was the problem with the car.

Malcolm

 

[ducati]

24 Valve engine has a different relay. The car runs very well then suddenly lost power - could just about restart it then it dies again - feels just like no fuel. I left if for an hour (until the RAC arrived) - it resarted - ran rough and then was fine for 250 miles. Did it again - restarted after about an hour ran fine - changed fuel filter - ran fine for 350 miles, did it again, restarted fine after 2 hours ran fine etc etc but now seems to be doing it after a couple of miles. Trouble is that each time it has been in the garage all is well (despite having it tick over for 3hrs on day1).

 

[television]

My head is screwed up today 24v, being involved in electronics I thought volts.

Do you have one or two fuel pumps.

Malcolm

 

[tom7035]

My head is screwed up today 24v, being involved in electronics I thought volts.



Malcolm

Oops!!

 

[kth286]

Ducati

The car EITHER


1. Splutters to a halt as if it is running out of fuel.

OR

2. It cuts out immediately as if the ignition switch has been switched off.


What happens - which is it - 1 or 2 ???????????????


Regards

 

[ducati]

Splutters to a halt, runs rough for about 30 seconds then dies. May start again for a few seconds then won't start.

2 fuel pumps

If I can't get it sorted it will soon appear on ebay! A great shame as it is faultless between breakdowns and has hardly done any miles (for a Merc)!

 

[leylandp38]

Hi Ducati, So, in answer to your original question, where is the relay located? I can't find it on my 1992 24v Estate either (300TE-24) and I know it has failed as I have had to bypass it with a direct wire to the fuel pump.

And if you now have a spare good one do you want to sell it?

thanks

Al

 

[leylandp38]

The answer - and some info on 24v models

For info of other 24v W124 owners out there, here it is (photo courtesy of Ducati):

- it is the tall box marked "MAS" with a black knob on top (twist to release unit from car).

What I have found out from Mercedes is that this little beauty controls not only fuel pump, but also aircon/climate, electronic auto box functions, and some engine management functions.

It does not appear at all in Haynes (but then, what does... ) and I believe it is unique to the high spec 24 valve versions (300-24 and 320) with the 5 speed electronic auto boxes.

There are several versions of the unit so be careful to get the right one. MB have confused things further by releasing replacement units that supersede earlier codes, so unless you get an exact match it's probably wise to talk to the dealer about the correct one for your car if you need it.

 

[stevelewis]

I have symptoms of the car stalling as if fuel or electric cut. This can happen randomly, even if travelling at speed. Is the relay the most likely culprit. In case someone has other pearls of wisdom, my cruise won't hold a speed, clock doesn't work properly and I have a mouse in my heating system (latter problems not critical but someone may have simple answers)

 

[mioba]

I would be looking at what the mouse has chewed through as a start. Get a torch and carefully inspect everything in the engine bay

 

[DREAMER NO2]

Steve you have started off on an old post ,,its going back to 2006 ... Steve what car do you have ? Steve you need to fill in your profile under your name to the left we dont know how to help you without this information