1985 Mercedes 280ce not running .

[carravagio]

Wondering if anyone can help /ideas my old Mercedes went in for service to garage prior to this I had some problems
it wasn't running well especially on idle it would cut out managed to get a second hand ignition control unit and that appeared to solve the problem.

However today the mechanic ran some tests and carbon monoxide running below1/2pct and the hydrocarbons 2000ppm
it seems the car has a spark will run few seconds and then cut out . they seem to think the problem could be the metering unit
it looks like previous mechanic has fiddle with it cleaning the carbon deposits .

this is a Bosch unit no 0438120115 it might be I have to buy a new unit or aftermarket or second hand if they cant resolve the problem .

any help ideas welcome bearing in mind im not mechanic, before I chased up the part needed to save costs and was lucky
these cars have a good reputation for reliability however it is 38 years old done only about 79,000 miles .

 

[mattkh]

..... hydrocarbons 2000ppm

Change the spark plugs.

 

[Uncle Benz]

It’s definitely worth checking that sufficient fuel is reaching the metering unit first. There is a strainer in the tank outlet that can get clogged. Usually the pump gets loud if this is a problem. The fuel supply line that comes up to the metering unit is secured with a banjo bolt. If the bolt has a raised circle on its head there is a tiny gauze strainer inside the bolt too. These can also get blocked up. Pump doesn’t make so much noise with that one. Failing that I’d do some pressure checks next and also check the injector spray patterns. The O rings on the injectors also get hard and let air in which will make the mixture weak. A squirt of brake cleaner detects that quite well

 

[bembo449]

i agree with the above , on cars of that era you need to be sure the fuel system is doing its job , could easily be a blocked fuel filter or something equally simple