W126 380 Fuel Pump Relay

[ivan1983]

Hi all,

I think I have a dodgy fuel pump relay and would like some assistance confirming this.

The reason I think the relay could be at fault is because it does not "prime" the system when I turn on the ignition.

I removed the relay and jumpered it and the pump ran.

The car starts on the button in warmer weather but when it gets colder it needs to be cranked for a bit longer. It also runs quite rough on cold days for the 1st 30s or so but i think I think I need to "tune" the CIS system to sort that.

Once started the car seems to drive normally, kickdown works, and the rev limiter works I also checked the cold start injector and this worked so parts of the FPR are working.

I have re-soldered the board with no change.

The only info I have found is for the later W126's do the earlier w126's "prime" the system as well?

Is there any diagnostic info or a circuit diagram out there that anyone has for a 1983 model that I could use or any pointers on how to troubleshoot the system, ie what voltages I should be seeing at the various pins or if its possible to bench test the relay.

If the older system is supposed to prime the fuel circuit and this is not happening I believe that the car is effectively being started by the cold start injector or whatever is left in the system. Once the engine is started/turning I believe the FPR is getting the signal and turning the pump on at this stage.

Any help appreciated as I would like to get this sorted before the cold weather moves in.

Cheers

Ivan

 

[219]

I've got a spare FPR out of a 420SE I broke ; if you post up the part no from yours I'll see if this is the same .

I'm happy to post it to you for you to try , and if it works , you can then send me whatever you think it is worth ?

I may have a pile of other W126 bits coming up for sale as I'm thinking of getting rid of my 500 .

I did advertise it a couple of months back with all the spares included , but never got any takers . The advert will still be in the classifieds section .

I will probably start listing the parts individually and see if any sell .

 

[ivan1983]

Hi Pontoneer,

I will pop it out and get a part number once I get home, do you have a ball park figure what you want for it in case it is compatible and does work.

Why are you thinking getting rid of the 500 and not the 280?

Just had a gander and it seems your advert has disappeared from the classifieds.


Cheers

Ivan

 

[219]

Hi Ivan , here's a link to the advert

http://www.mbclub.co.uk/forums/classifieds-cars-sale/155352-w126-500sel.html

I have already sold the 280 and the 500 has been lying for about 10 months doing nothing now .

I was keen to try to sell the car and all the parts as a job lot , but since there has been no interest , I think I'll see if I can clear the parts and then offer the car on its own at a lower price . As you will see from the pictures it does need work !

You will see the collection of relays and other electronic bits some way down , you can probably see from the photo whether what I have matches .

As for price - whatever you think is fair ? say £20 + postage , which I guess is a fraction of the cost of a new one ?

I may give the ad a 'bump' to bring it back to the fore .

 

[ivan1983]

Hi Derek,

Wow that is an extensive list of parts!

I didnt realise you could get the W126 without SLS,

That seems like a reasonable price although Im not sure its compatible with my part.

The part I have has the following stamped on it

001 545 34 05

5950/min 8Zyl.12V

896376 83 Kickdown

I might be interested in the window motors as well if the will fit a 1st gen W126.

You should definitely give your advert a bump as Im sure a few people will want some of those bits!