The Definitive Fuel Pump Relay Questions Thread

[Squabble]

Here's my situation: flying out to pick up a 1984 Euro 280E that once in a great while has some no-start issues.  I'm trying to gather a couple parts to bring with me for the 9 1/2 hour drive home with her.  This will include a fuel pump relay and probably the pump itself.  So I'm trying to get some information regarding the right relay to buy.  I've been through something similar with my 1978 Cali. version 280CE and there were a lot of mixed messages concerning what exact relay to buy and where it goes.  So here's the information I have plus some questions:

It appears that the US market w123s have the relay on the drivers side of the engine compartment, near the firewall under a black plastic box.  it's an "ice cube" relay, perfectly square, with five pins, and silver colored.  

The Euro Spec RIGHT HAND DRIVE w123s have almost the exact same set up, with the relays on the left side of the engine compartment.

Here's what I don't know: where is the relay located for a Euro Spec left hand drive car?  Is it in the glove compartment as I've read here and there, or is it under the steering wheel?  Is it black with six pins in and taller than the ice cube relays?  That is, does it still have a square base of the same size but much "taller" than the ice cube version?  Or, is it rectangular in shape, with the pins coming out of the longer side, not the square base?

Nutz, where is your relay located?  what shape and color is it?  I assume the '81 Euros will be the same or similar to the '84s, correct?

Anyone know anything?  Can you look at your car and let me know?  Thanks!

EDIT: Attached some images of the engine bay of the car in question.  It appears to have a tall black plastic box near where the typical black plastic box of relays usually sits.  This car has manual windows and a manual climate control, along with possible other low-option stuff.  Maybe that's why there's less relays?  Either way, do you think the tall black relay goes inside the tall black box?  Think it's the usual six pin one, like this: http://www.partsgeek.com/mmparts/fuel_pump_relay/mercedes/280e.html?

[nutz4benz]

I'm stumped. Does the cover slide off?

[Squabble]

Don't know, and there's no way of knowing before I fly out to get it.  It's two states away and the it's being stored away from the owners residence as well.  Quite far and we'll be getting there at the same time, he won't be there before that to check.  I need to go on other people's experience. 

Where is your fuel pump relay located?  What does it look like?  Anyone???

[Squabble]

Alright, my research has found some results!

Early w123 gassers, up until 1981, all had ice cube five pin relays for everything, including the fuel pump relay.  they were located in a rectangular black box above the wheel well, on the drivers side no matter if it was LHD or RHD.  Usually around 5 relays in the box depending on the cars electronic options.  The Meyle part number is: 014 054 0027 but that's the only number I found.

Beyond 1981, things changed.  Some still have the ice cube relays and some changed to the same relay the w126 m110's had, the 9 pin rectangular box.  You can see it in the m110 manual provided on this site under the Checking Fuel Pump Relay section.  It looks like the V8 box and has 9 pins that connects to a 12 pin box.  Original part number 001 545 6805.  This guy is rather rare and very expensive for a relay.  It was suggested that if it's bad, it's better to take it apart and solder the connections rather than search for and pay for a new one.  Or you can just jumper the pins, which I'll probably be doing for my ride home!

If you do have the kind with the w126 style rectangular box, it was explained to me that you can use the 6 pin relay, part number 001 545 0705 and just stick it in the one end and leave the other pins uncovered.  It's the relay that's still for sale on most sites: http://www.partsgeek.com/mmparts/fuel_pump_relay/mercedes/280e.html.  I might be assuming here as well, but based on how prevalent that relay is, I think some of our cars might use that one exclusively as well?  Perhaps this is the one that I've heard about going up under the kick panels or behind the glove box? 

However, I did find this original part number: 001 545 4305 which leads to this current part number by KAE: 3.301.310 as the updated relay, found here: http://www.autohausaz.com/search/product.aspx?sid=ywrmmket2qat5znftaqm3f45&partnumber=001%20545%204305.  Again, that might be exclusive to the w126s and r107s with the M110 engine though.  I'm going to do some further research.

It's an odd mystery but I'm getting it sorted out!

[nutz4benz]

I noticed today that I have that relay box too on my 81 280E. 9 pin if I recall correctly. I'll take a pic of it and post it in a few.

[Squabble]

Okay, some further research brings new info to light:

The w126 style relay, shared by some euro 280Es, has the original part number 001 545 6805.  As stated, it's insanely rare to find and expensive.  I found another option, part number 001 545 4305 which now defaults to a KAE relay, number 3.301.310.  These relays will work, but are unreliable and can be expected to last about a year (anecdotal evidence).  I haven't been able to find an original part for that number. 

That about sums it up I think...