W124 fuel pump relay

[trev9712]

I have a 1986 W124-300 which has stopped suddenly.
I cannot hear the fuel pump buzz when the ignition is switched on.
If i connect a direct feed to the pump,it works ok and the car runs, but as soon as the power is taken away,it stops dead.
Would the problem lie with a relay for the pump?
There is a large relay behind the fuse box,next to the flasher unit,but there are also other relays behind the battery,one of which has a fuse on top of it (the fuse is ok)
Which of these is the most likely culprit?

 

[paulcallender]

The fuel pump relay is combined with the kickdown relay, so unfortunately it costs twice as much as it should be. I can't remember exactly, but I think there's something vaguely gearbox-related on top of the relay. Its recognisable because its double the size of a regular one.

 

[tom7035]

Hi Trev.
I think the relay you are looking for is under the fusebox tray. Take off the fuse box cover, then remove the six screws holding the tray underneath and there is your assortment of relays at the back. (But someone else will have to tell you which one it is, or perhaps a gentle tap with your screwdriver handle (ignition on of course) may jog it into life at least temporarily so you can identify it).
Tom.

 

[Richard Moakes]

The fuel pump relay on that car is behind the battery, by the OVP relay.

It's double width, and you will see some writing on the top about 6-zyl and kickdown etc....

As said previously, it's combined with the transmission kickdown relay, who knows why?

If you are handy with a soldering iron, open it up and reflow the joints, you could save yourself a tidy sum.

Good Luck,

Richard

 

[tom7035]

I'd take Richards advice above Trev - I was going by Haynes manual which has once more been found 'wanting'!
Good advice also on attempting repair - 'dry' solder joints commonplace faults on all things electrical.
Cheers, Tom.

 

[paulcallender]

Yep, by all means try out repairing the relay, it could save a good amount of money. Just be aware once refitted though. Its possible that the solder joint came apart due to heat, due to a faulty component. Once you've fixed and replaced the relay, start the car but have a fire extinguisher handy! And also, some way to quickly disconnect the battery too, since it would be difficult to quickly pull a hot, smoking relay off its location. If you start it and it works (no smoke/heat, etc) then I can't see why not to run the car as usual.

 

[trev9712]

two relays

Behind the battery there are two similar relays with the following numbers:
0025452705 [02] 6Zyl 6350/min KVS 05370222 Kickd
0025451305 Klima 6Zyl 12V 05995211
Am i right in thinking that the fuel pump relay is the first one? :???:

 

[Richard Moakes]

Spot on the one marked 0025452705 [02] 6Zyl 6350/min KVS 05370222 Kickd is the fuel pump / kickdown relay

Good Luck,

Richard