R107 SL500 Fuel Pump Relay

[mct_cars]

Thought I'd share....

So, last year I started having the usual issues with the fuel pump relay - basically, when you turn the key, you don't hear the whoosh of the fuel pump, and the engine turns but obviously it doesn't start as the fuel pump isn't on.

I took the relay out, re-soldered it (although there was nothing obviously dry in there), put it back in and hey presto, fixed.....

Until I went to start the car earlier on in the week, same issue so I took it out, cleaned the pins, accidently dropped it on the ground, refitted it and again, fixed....

But this spurred me on to find a replacement....

Now as anyone who has looked for an original, they are horrendously expensive from MB. The cheapest second hand "good" one was around £50 (someone asking £160 too!). So I thought I'd have a punt on one of the OEM ones from e-bay.

So I did a little research and noted that a load of sellers have part number A0035452505 as a direct replacement for the original (A0025451605). The part looks like a URO part (I've used their seals before and they are a good fit), and for £22.80 with a 2 year warranty, worth a punt.

So tonight I went to fit it and noticed that the unit is pretty much the same but the new unit has an extra pin- basically the old unit has a row of 8 pins and another row of 3. The new unit has a row of 8 and then a row of 4.

Thinking what the hell, I fitted it anyway.... and it works. The car started fine. I revved it and it revved, and most notably, I've been suffering a slightly high idle (around 900-1000 rpm) which I was pretty certain was down to vacuum, but with the new unit, the idle settled down to more like 700-800.

So I guess the only questions I have is, what is the extra pin for and will I see any issues in using this relay? Be interested in peoples input!

 

[Pluto]

Most relays have their schematic printed on the relay---what is designated for that pin??

 

[mct_cars]

Neither the original merc part or the replacement have anything written on them pin-wise.

 

[Druk]

The A003 part number shows up on an EPC search as suiting various 126 and 463 vehicles. The A002 part number shows as for 107 and 126 vehicles so there is obviously an overlap between the 107 and 126 parts bin.

The likelihood is that the extra pin is for something on a 126 which is not required on a 107. If it's fitted and it works I would ignore the pin and get on with happy motoring .

Hope that all makes sense.

 

[ray_hennig]

So I did a little research and noted that a load of sellers have part number A0035452505 as a direct replacement for the original (A0025451605).

This may be of interest:
RELAIS DE POMPE D'ALIMENTATION - SL R107 / W126 | Auto4

I searched the part number for a leather seat cover for my 124 coupe and these people had one. New Old Stock and €42 delivered to the door. MB list price around €650!!!

The moral of the story is to Google the part number of the bit you want. You might strike lucky.

RayH
AAAGGGHHH! Just noticed that stock is now zero. Sorry to raise hopes. Still worth Googling though.

 

[roastbeef]

I purchased a fuel pump relay recently from ecp for my 190e the guy on the phone said it may come with a extra pin but would be fine it came with the exact same as the old one. Also the actual price was way under what they was advertising it for on there Web site or eBay listings so may be worth giving them a call if you are looking for one

 

[Pluto]

Neither the original merc part or the replacement have anything written on them pin-wise.

Very odd, in any event the 002 545 16 05 was replaced twice. The current part number is 003 545 01 05.

If you post a VIN I wil search the wirings

 

[JPJFA]

Thought I'd share....

So, last year I started having the usual issues with the fuel pump relay - basically, when you turn the key, you don't hear the whoosh of the fuel pump, and the engine turns but obviously it doesn't start as the fuel pump isn't on.

I took the relay out, re-soldered it (although there was nothing obviously dry in there), put it back in and hey presto, fixed.....

Until I went to start the car earlier on in the week, same issue so I took it out, cleaned the pins, accidently dropped it on the ground, refitted it and again, fixed....

But this spurred me on to find a replacement....

Now as anyone who has looked for an original, they are horrendously expensive from MB. The cheapest second hand "good" one was around £50 (someone asking £160 too!). So I thought I'd have a punt on one of the OEM ones from e-bay.

So I did a little research and noted that a load of sellers have part number A0035452505 as a direct replacement for the original (A0025451605). The part looks like a URO part (I've used their seals before and they are a good fit), and for £22.80 with a 2 year warranty, worth a punt.

So tonight I went to fit it and noticed that the unit is pretty much the same but the new unit has an extra pin- basically the old unit has a row of 8 pins and another row of 3. The new unit has a row of 8 and then a row of 4.

Thinking what the hell, I fitted it anyway.... and it works. The car started fine. I revved it and it revved, and most notably, I've been suffering a slightly high idle (around 900-1000 rpm) which I was pretty certain was down to vacuum, but with the new unit, the idle settled down to more like 700-800.

So I guess the only questions I have is, what is the extra pin for and will I see any issues in using this relay? Be interested in peoples input!

Thought I'd share....

So, last year I started having the usual issues with the fuel pump relay - basically, when you turn the key, you don't hear the whoosh of the fuel pump, and the engine turns but obviously it doesn't start as the fuel pump isn't on.

I took the relay out, re-soldered it (although there was nothing obviously dry in there), put it back in and hey presto, fixed.....

Until I went to start the car earlier on in the week, same issue so I took it out, cleaned the pins, accidently dropped it on the ground, refitted it and again, fixed....

But this spurred me on to find a replacement....

Now as anyone who has looked for an original, they are horrendously expensive from MB. The cheapest second hand "good" one was around £50 (someone asking £160 too!). So I thought I'd have a punt on one of the OEM ones from e-bay.

So I did a little research and noted that a load of sellers have part number A0035452505 as a direct replacement for the original (A0025451605). The part looks like a URO part (I've used their seals before and they are a good fit), and for £22.80 with a 2 year warranty, worth a punt.

So tonight I went to fit it and noticed that the unit is pretty much the same but the new unit has an extra pin- basically the old unit has a row of 8 pins and another row of 3. The new unit has a row of 8 and then a row of 4.

Thinking what the hell, I fitted it anyway.... and it works. The car started fine. I revved it and it revved, and most notably, I've been suffering a slightly high idle (around 900-1000 rpm) which I was pretty certain was down to vacuum, but with the new unit, the idle settled down to more like 700-800.

So I guess the only questions I have is, what is the extra pin for and will I see any issues in using this relay? Be interested in peoples input!

 

[JPJFA]

I too have had the Fuel Pump relay issue on my 1988 R107 SL 500. Bought a replacement that has solved the initial starting problem (no fuel pump). However, I now have a hot start problem. It will not start at all until allowed to cool down for an hour or two - then works perfectly again. Any ideas? (BTW tried swapping back the old relay - works sometimes!)

 

[alabbasi]

URO is junk. Keep a known good spare in the glove box