w124 1988 12v 300ce misfire 4000rpm +

[serviceyourcarcouk]

Right new to here despite owning 2 mercs, have bought a new one a 1988 300ce coupe. blue, lowered nice wheels, and a bargain at 600 quid!

However she has a few problems, first of all she wont rev above 4000 rpm, whether your stood still or under load she kangaroos all over the show.

Secondly she cuts out now and again when warm, think this might be something to do with all the tape on the ignition leads so will sort that today hopefully.

There are a few electrical faults, os rear window doesnt work, interior light playing up, and electric aerial not working but being a mechanic by trade and owning a garage workshop and 10k's worth of diagnostic equipment most of these faults should be easily fixed.

Its the misfire above 4000 it cuts all cylinders and kicks back in once revs fall below 4000. Now if this was a newer car i would have a better idea however being only 25 i havent ever had the misfortune of having to do too much with bosch k systems which are semi mechanical and notoriously hard to diagnose faults on. So people can anyone point me in the right direction?

thanks in advance.

 

[television]

Possibly a wrong fuel pump relay has been fitted,,all MB's cut at 4k in N, with the wrong fuel pump relay the car could do it in D, and this was one of the first post that I answered on this forum

 

[serviceyourcarcouk]

now there is a route that i was looking down, i know that they cut at 4 k when not in drive. was thinking possibly selector switch faulty?
then i was testing it today and had it jacked up looking at a small leak on the fuel pump i had found. I started the vehicle and it ran out of fuel whilst it was jacked up, let the jack down and it started and revved fine. All was well until i put more fuel in it, moved the car out of the workshop and did the same thing again! other thing it has been doing is idling rough and revving slightly, then cutting out when left running for 5 minutes or so.
I take the the car to the petrol station on the way home, start it up and it revs fine i get down the road approx half mile and it cuts out completely, starts again and limits at 4000 rpm again.
then revs fine then limits again???
Ive only owned the ****** thing a week and already i feel like crushing it!!
Working on it being a loose connection poss fuel pump/fuel relay. or water in fuel maybe? seems to rev to 4k then sometimes 4.5k then kangaroos. Gonna try a fuel filter on it tommorrow and have a look at what the fuel is like that comes out of it. Have pretty much ruled out spark problems as i had it on the oscilloscope and primary and secondary ignition voltages are mirror imaged and when missing the spark voltages remained constant.
Determined to get to the bottom of this one!! Any more pointers much appreciated.

 

[television]

077 in the link,,take out the fuel pump relay and bridge pins 30 to 87 and the car will run with,out it.


http://www.detali.ru/cat/oem_mb2.as...GM=717.430&CT=F&cat=508&SID=54&SGR=040&SGN=03

Later cars have 2 small fuel pumps and this was a standard mod as against the 1 larger one.
If you take the fuel pump off and put the head in a bowl of diesel, then run it backwards,it will clean it out