merc estate 200te problem with dying and blowing fuel relay

[bruceybenz]

Hi all im new to this site but if possible would like to try and solve a problem with my estate if at all possible any help is very much appreciated. I was driving the other day and all of a sudden the car just died i lost all power and elctrics and came to a halt i managed to get the car to a petrol station and call someone out have a look he diagnosed that the fuel pump relay had blown but this still didnt explain why the car died so i bought a new battery and relay and put them on and it was fine for about 2 days or approx 40 miles then the exact same thing happend again i contacted the mechanic who when told was stumped and couldnt shed any light on it for me so it seems ive hit a brick wall if anyone out there has had similar problems and could help me out or can even realise what it is PLEASE HELP IM TOTTALY LOST WITHOUT MY CAR !
THANK YOU!!!!!!!!!!!!!

 

[joe bloggs]

Sounds like one of the main supply connection points, these are bolted junction boxes for the main supplies. Start with the one beside the battery, open the plastic cover and check the 10mm bolt is tight and the cables are ok, next one is on the other side below the servo,, bit more fiddly, the other one is below fusebox, best checked from inside the car roughly above accelerator pedal. CAREFUL WITH THESE, UNFUSED, best to disconnect battery earth when checking. While at battery check neg cable bolt to body is tight. Another trouble area is the main alternator cable where it is held on the o/side chassis leg, it can break over time with the engine movement.

(I am assuming we are talking about a 124 here btw.)

 

[jberks]

It doesn't sound like you have a clear view on what is actually failing. If it's the battery losing charge then that will be an alternator problem, if its the fuel pump relay then that's another - but not twice. The only way I could see that they could be linked, would be if your alternator is overcharging and the fuel pump relay is particularly sensitive. But then a new battey shouldn't cook in 40 miles unless it's off the scale and other things would be popping too. A new battery will mask a number of electrical problems for a few days, (put a new one in a granada once, turned the key and blew up the starter motor), so I suspect the problem hasn't changed, just disappeared long enough to get you off the forecourt. If your mechanic is stumped, get yourself another one. If you say where you are, I'm sure someone will know a good local specialist who can get you back on the road pretty quick.

 

[joe bloggs]

Cant be the fuel pump relay if the car lost all electrics, possibly not charging though, put a voltmeter on the battery, should read somewhere between 13 and 14.5 volts when engine running, should be above battery voltage at least.