Le "français" 350 SE no start !

[s class]

Denis,

What condition is your ignition coil in?.  I have had these sorts of symptoms on a 280S - very difficult cold starting, unreliable hot starting and poor uneven idle in all conditions.  Tried everything imaginable and it turned out to be the coil.  Failing that, I had similar problems on a k-jet 280SE.  In that case the problem was the distributor cab and rotor.  They were brand-new (made in Taiwan cheap stuff).  But since they were new, we never considered them as a problem.  In depseration I fitted an old Bosch cap and rotor that were lying around, and the problem was solved 100%.

Mercedes don't like non-Bosch bits. 

Ryan in Afrique de Sud.

[Denis]

Thanks S class

I am going to give the ignition a real rundown. I happen to have a spare coil so that idea is going to be tested and last but not least, substitute a "repaired" manifold pressure sensor for the existing one.

What drives me NUTS (sorry for the pun Nutz  ) is that the car runs VERY WELL at speed, not a trace of a hesitation and good power, that really mystifies me 

I want a SMMMMMOOOOTTTTHHHHHH S class like it has 8 cylinders not 3-4


Au revoir

Denis

Paris, France

[Denis]

OK, this must be the end of thsi thread !

Seems that "Von Humboldt" has cured itself 

All I did is tweak the ignition timing to a slightly better setting and everything is OK now...

I am amazed at how bizarre this car can sometimes be 

Thanks to all who really jumped in to help

Denis

Paris, France

[John Hubertz]

Denis!

Congratulations!  I've faxed the confetti for "le celebration!".....

Hey, don't feel bad - I had a 4.5 in a 107 chassis (the SL) that did the same damn thing.  It just wouldn't even TRY to start...  I rotated the distributor finally and it started and never acted up again. 

That is just weird stuff - I wonder if the EFI is the culprit at the core - as my car had that system too.

[Denis]

Hello fellows

Well I did three things that I believe were directly related to the problem :
- New fuel filter
- New fuel pressure regulator
- Clean/lube the injection trigger points in the distributor.

The EFI takes its core commands from the injection trigger points. If they are oily or dirty, problems MUST appear.
In my opinion, they are a maintenance item : they need cleaning after X years; What is X ? no idea 

Denis

Paris, France

[Denis]

Surprise, surprise !!!

Ye olde Von Humboldt is at it again 

The bottom line is that it only happens if the car has not been started in 8 hours. I suspect that the fuel pressure in the ring is too low and that the residual pressure is lost.

OK, the fuel pressure régulator (new) deals with on end (back to the tank return).

At the other is the fuel filter (new) going back to the fuel pump. Now my model of fuel pump has a check valve  in the outgoing connection to the entry of the fuel filter.

If this check valve leaked, wouldn't that loose all pressure after a while ?

If so, where does one find a replacement for the check valve ? not a new fuel pump 

Again, the car performs very well otherwise.

This is really getting to be a problem 

Denis

Paris, France