Hi!

I bought a w124 300e project car that really wont start. i got it to start once with starter fluid and it ran at 2000 rpm but as soon as i gave it slightest throttle it would just stall and not rev at all. found out that i had dual fuel pumps one of the fuel pumps didnt work changed to a working one so now both is in working order, but still no start or very hard starting if it starts just runs for 1second without any idle or throttle response at all new dist cap,spark plugs and IAC. could i have a clogged tank or something?

Runs good and even idles fine with starter fluid.

would really appreciate all help i can get.

 

First i would get a fuel pressure test done .. then if the pressure is correct ok -- when was the last time that the fuel filter was replaced -that could be blocked up . Remove the return to tank pipe from fuel distributor ,and see if the fuel is return from metering head and distributor back to the petrol tank. . High revs are vacuum related so check all small vacuum pipes and connectors for splits .Check all fuses -give them a turn in the holders ,. Could be a hundred thing to stop your engine starting . Fuel pump relay - faulty crank position sensor . Are the plugs wet -pull one out and check it .

 

Hi, new here but have similar problem with a 300e W124 m103.
Where do you check the fuel pressure ? What should it be? Can fuel pressure be monitored during starting? I am thinking I have a fuel supply issue but can hear pump prime have checked fuel is reaching metering head and engine will run but only for a couple of seconds and no higher than about 1500 rpm.
My car was surging on idle and running erratically. Would run for 10 to 15 minutes and then splutter or stall, if it didn't stall it would run for another period. Ran ok at medium and high revs when engine was cold or hot. Carb cleaning spray made no difference.
1st thing I tried was adjusting screw down through hole in air filter . It had no noticable effect winding in or out but may not be where it was originally set. Is there a start set position for this screw.
OVR removed (connections cleaned) and reseated - fuses both good.
Fuel pump relay removed (connections cleaned) and reseated.
No change.
To try and cure problem I then removed checked, cleaned and lubricated all the throttle cables brackets/linkages. Straightened out the brackets at a couple of places where throttle cable adjuster and gearbox link adjuster are located (white arrows in picture) as they were mishaped. Reset throttle cable so that bracket sat on stop (at yellow arrow) and adjusted gearbox cable link to remove all slack. Removed microswitch as the rubber covering the plunger had perished. Cleaned tested and replaced (without the perished cover) this switch actuates as soon as the throttle is pressed now - not sure if that is correct!
Retesting revealed it was now worse and car only runs for 1 or 2 seconds.
Removed and cleaned Idle control valve, tested actuation ok, added jubilee clips on rubbers to ensure no air leaks.
Removed cleaned tested cold start valve and have good wide spray during cranking. Refitted.
Removed and cleaned Fuel pressure regulator. Refitted.
Checked the K tronic fuel filter which was totally clean. Refitted
No improvement.
I keep going back to thinking the throttle linkage setup must be causing the problem but cant see what might be wrong.
NOTE - Crankshaft position sensor, Rotor arm, distributor, coil, ht leads and plugs are all less than 3 months old.
Have seen various post about checking manifold vacuum does that seem like it might present these symptoms?
Clutching at straws now so any help appreciated.
Dave

 

You messing with parts that are set from the factory and no way should be changed .There is 100 items on you engine that can cause this. Vacuum pipe cracked or the rubber coupling split . Earth points not earthing due to rust in the lug on the end of lead and to the car body-clean them and grease them .. I think you running in closed loop mode now due to the adjustment you did , as nothing in the adjustment you do is changes anything .Its hard to find these problems .Checking everything first before you change anything . Do you have a manual? if not google this = Model 124 Maintenance Manual Index go through it to understand a little more. The fuel pressure relay can be bridged to rule that out you wire 7 and 8 pins on the relay with a little copper wire then fir it back in it socket .If it continues to run remove this wire right away .This wire keeps the pump running all the time and will pump fuel in to the manifolds -so important to take the wire off asap after testing .If engine runs without stopping it rules out the fuel Pressure relay .To test fuel pressure information it is in the free manual .

 

Thank you for the pointers. I thought there would be a manual available somewhere.
The only parts I messed with appeared to have been damaged where someone may have forced the cable blocks out from the rectangular holes, and were very minor. I reset the stop and cables as per another forum post and as far as I know its set back to where it was. The strange thing is if I detach throttle cable and gearbox link there is no difference so I kinda ruled out the tweaks as causing the new problem. Before changing the ignition parts I had checked out fuel system items multiple times and could not find anything definite that was wrong. I will find the pressure test info and try that. I know I have fuel flow at prime but was curious about whether the pressure is correct. Done as many earth points as I could find and have tried other batteries also.
Dave

 

You can remove the fuel return to fuel tank pipe to see if fuel is returning ,,if it is its getting in to the injectors..,Look in the manual as to how to check fuel pressure also Youtube videos are good for the procedure /.