? broke relay to fuel pump

[jerryB]

sorry if this is in the wrong tread.

I have just bought a 123series 230E auto petrol , and i am having a problem with starting it . 3 out of 4 times it will start no problem but sometimes when i turn on the ignition the fuel pump does not come on and so will not start and has to be left , if i come back after 1/2 hour or so it then starts with no problem
Someone said it could be the relay ?
Does this mean a new has to be put in or can it be fixed ?
If a new one has to be bought any ideas how much they are ?

Or does anyone have any other ideas , i have put a new battery in and fuel
thanks for the help all

 

[Brian WH]

Moving to engine section.

 

[guydewdney]

the fuel pump relay (part 001 545 07 05 - 100 dollars approx) is just in front of the fuse box, left side of engine bay. get an assistant and a mutimeter to check that its being operated / powered.
if being powered, but pump not running, then relay dodgy probably.
if not being powered, is there an aftermarket alarm? often uthese use a cut off to the relay to immobilise car.
you CAN pop open most relays and clean contacts with a ear bud and neat alcohol (or cheap vodka ) - but its risky

 

[jaymanek]

mines mechanical pump, not sure on the 230 though.

jay

 

[V12]

Guy, the location is dependant on the year of the car.
On most W123's it is located just under the dash, above the bonnet release catch in the passenger footwell...But i think it was the last 2 years of production they reloacted them to infront of the fuse box.

If you pull the relay out and short across the two centre most pins, that will permanently live up your fuel pump, and you will hear it running, do not leave it like this for two long, it will just build up more and more fuel pressure if you are not turning the engine over.

The car can be run like this, with a piece of wire or anything, but it is a quick easy diagnosis as to whether it is faulty or not.

They are very common to become faulty, and it starts as you described and after a few months you will get nothing from it, others do just pack in.

They are about £80 new i recall...

 

[jaymanek]

Ricky - do you know which ones have an electric fuel pump? Mine doesnt have it, 1980 older type 115 engine... was wondering why the need to have one.

Jay

 

[V12]

Jay, anything fuel injection has one, carb cars have a manual one...

Just reminded me...big doh...you know what i haven't sent!!

Ricky

 

[jerryB]

Thanks V12 for the answer I'll get a new one put in on tuesday after the bank holiday . Last thing I want is for it to suddenly stop working with a 16 wheeler behind me

 

[jaymanek]

Cheers Ricky- I have hotwired it for now, but would be nice to have a proper switch! Its amazing- It was standing for 6 months (another 123 i have for spares), it fired straight up, and hasnt missed a beat!

Cheers

jay

 

[grahamf505]

W123 Fuel Pump Relay problems

Looks like I've currently got the same problems on my '83 230E.

Its tripping in and out all the time now. I'm trying to get a replacement secondhand one for this weekend, but am struggling.

Jay, I know you are in Coventry like me, do you have a spare knocking about or know where I could pick one up without paying full Mercedes dealer prices? German and Swedish cannoit supply and Mark Cosovich cannot ship me one till next week.

As an alternative, I could hotwire as long as I don't damage my pump. I am replacing the fuel filter before I do anything else as I understand that if this gets blocked it can cause the relay to fail as it overheats from staying on too long caused by the increased load applied by the fuel pump in pushing the fuel through a partially blocked filter.

Graham