300CE 12v engine problems

[pmitchell]

Hi All,

Just signed up in the hope someone can help me. My uncle has a 1992 J 300Ce 12v. It developed a problem where when it would reach operating temperature, it would misfire and then stall. If you tried to start it again, it wouldnt. Leave it 10 mins and it would fire up again...2/3 mins later, stall again.

Anyway, the car has been stood for about 4 weeks and now it will not start even from cold - same sort of performance trying to start it now, as when trying to start it from hot when this problem first occured.

There is plenty of spark at all 6 cylinders. Fuel delivery upto the injector pump is fine, but then there is virtually nothing pumped from this to the injectors. The occasional drip, but nothing more. I have removed the pump and am due to send it away for inspection.

Just after any experience of this, and whether any of you know of any other problems it could be. There is what looks like a cold start injector and when I undid that, fuel came out at the correct pressure. The other 6 lines tho produced virtually nothing.

Never worked on a Merc before, but know my way around an engine bay, and wanted some advice before I send the pump away to be checked and possibly replaced/reconditioned.

It has come to me after 3 garages have failed to locate the problem after replacing various sensors etc.

Any help will be much appreciated.

Kind Regards

Paul

 

[Leylandp76]

In the 'various sensors etc' that have been replaced, does this include the ECU?

 

[pmitchell]

No it didnt include the ECU. Should I try this?

Regards
Paul

 

[Leylandp76]

I didn't read your original description properly, sorry

Your descriptions seem to suggest a fuel delivery problem I agree. Not had this with my Merc but with my older Volvo 265 using L-jetronic (similar to K-jetronic but lower pressure) a new main fuel pump solved a similar issue. The cold start injector is fatter I think and therefore requires less pressure to operate.

Have a look at www.gsfcarparts.com for reasonably priced fuel pumps.

Alistair

 

[Leylandp76]

oh, do get your pump checked first however

 

[Spike]

I had a very similar problem on a bike once... it turned out that the airfilter was so dirty that it was acting as if the choke was permanently stuck on.

When the engine got hot it was running so rich that it would die. when cool it would run like a charm. Wouldnt take a minute to double check that you havnt got a birds nest or something stuck in your air filter box.

Another quick check, try running the car with a tempopary filler cap. If yours is blocked it could also show the same symptoms.

Failing the above, you are going to have to look at the electronic side which is best left to the professionals. Where do you live, perhaps we may be able to recommend someone.

 

[Arnie]

The engine is most likely fitted with a Bosch KE Jetronic. The ECU doesn't do much here, except alter ingition timing, so if you don't get anything from the injectors, it will be a "mechanical" problem.

Check the pumps and solenoid valves and then check the injection system. The jetronic is mostly mechanical in operation and there is a lot of data on the internet or manuals can be obtained from BOSCH.