cold start problems

[Africa450slc]

Hi ;

I am new to this forum and live in south africa.

I have a 1979 Merc 450 SLC and experiencing cold starting problem.If i start when cold the engine truns and does not fire, seems like no fuel.But if i add a few drops of fuel into the pot it fires.Thereafter i can start with absolutely no problems.During the first few minutes of the engine running there is a like a flat spot when i rev the engine.But this disappears when it is warm.When i drive it it goes well.

If left overnight; i have difficulty starting it.any suggestions and ideas on what i could do will be apprecaited.

regards
collin

 

[MIW615]

Hi ;

I am new to this forum and live in south africa.

I have a 1979 Merc 450 SLC and experiencing cold starting problem.If i start when cold the engine truns and does not fire, seems like no fuel.But if i add a few drops of fuel into the pot it fires.Thereafter i can start with absolutely no problems.During the first few minutes of the engine running there is a like a flat spot when i rev the engine.But this disappears when it is warm.When i drive it it goes well.

If left overnight; i have difficulty starting it.any suggestions and ideas on what i could do will be apprecaited.

regards
collin

Hi and welcome to the forum, if I am not mistaken your car will have K-Jetromic fuel injection, you must have a FULL pressure test carried out by someone familiar with this system. There are many components that make up the system and the fault described could be more than one component.

 

[frank133]

Hi mate ,had the same problem with my 190e,I have changed a lot of the components to do with the jetronic injection system,the best improvement came when I renewed the spark plugs,the car is almost spot on starting,but I think I also have a fuel pressure holding problem,I suspect the fuel accumulator on mine.to be honest there is nothing left for me to change.As MW says its hard to pinpoint one part that will sort it out

 

[mattkh]

Hi
check the cold start injector.

 

[television]

Your car has a cold starting device that is operated when the key is turned, normally wired from the starter motor

 

[Africa450slc]

Cold STart

Hi Guys;

I opened the fuel line from the distributor to teh cold start injector ; this was dry .Is that normal.The return fuel line from the distributor to teh fuel tank was also dry when i loosen the nuts at teh distributor.However there was enough of fuel dripping whe i loosened the fuel inlet line to the distributor.

Could tthe problem be that ni fuel is being supplied to teh cold start injector?
Where is teh cold start relay for teh 1979 450 SLC ?

thanks in advance for teh suggestions.

regards
collin

 

[MIW615]

Sorry I can't tell you of the location of the relay, but the operation of the cold start injector relies also on a signal from the thermo time switch. Basically the cold start injector is there to aid the starting of the engine fro cold and is located into the inlet manifold, this sprays fuel into the engine at systems pressure when the engine temperature is cold and the starter motor is activated. The length of time that this additional injector sprays is determined by the engine's temperature, seen by the thermo time switch.
The thermo time switch provides the earth path for the cold start injector via a heated bi-metalic strip, this heater is activated by a voltage from the starter motor. As the strip heats, over a period of approximately 8 to 10 seconds (when cranking only), the legs on the bi-metalic strip separate and the earth path is lost.
A warm engine will perhaps only require 2 seconds before the circuit is broken and a hot engine will already show open circuit. This simple circuit is to avoid the engine being flooded when cranking and the additional enrichment only given when essential.

 

[Wayne_Gibson]

Hi Collin

I am almost the owner of a 1980 450 SLC, and I am also in South Africa. I am a member of the Mercedes-Benz Club of South Africa. Are you a member?

Please check out our website: www.mercedesbenzclub.co.za

Kind Regards,

Wayne Gibson
1969 Mercedes-Benz 230 (W114)
1970 Mercedes-Benz 280 SE (W108)
1980 Mercedes-Benz 450 SLC (C107 - Coming soon!)