W123 280 CE warm starting

[stever]

Hi all

I have a starting issue on my CE that seems to be getting progressively worse:

1. Cold starting in winter or first thing in morning is absolutely fine
2. Hot starting (e.g. re-starting within 30 minutes) absolutely fine

The problem comes either a) when the car has been parked up during a warm day, or after letting cool down for more than an hour or so after a run. It needs lots of cranking and then runs very rough (sounds like only 3 or 4 cylinders) but settles down after a couple of minutes. Does anyone have some suggestions as to the cause? I did wonder if it was a fuel pressure problem.

 

[BlackC55]

It does sound like a fuel pressure problem. A guage needs to be put on there to check it.

Have a chat to www.124works.com

 

[stever]

I've been thinking about this some more. On my car, attempting to start with the auto selector in "D" is prohibited, however, the fuel pump will run. Presumably doing this should re-pressurize the system and allow the car to start ok when the auto is returned to "P". In fact, this doesn't make any difference - is it possible that leaky injectors are causing the problem?

 

[bigasotonuk]

Hi,
I had similar problem on Porsche i owned years ago. It proved to be the injectors not holding pressure leaking fuel into the combustion chambers effectively flooding the engine till the fuel evaporates off.
When you cold start it you hear the fuel pump wind up immediatly for about 5-10 seconds building the fuel pressure up enough to start.
I don,t think its your fuel pressure regulator as this would,nt cause it to fire-up the way yours is, as it only controls the pressure by dumping excess fuel to the return tank fuel line.
If you replace the injectors they should be replaced as a complete set I.M.O.

 

[stever]

Thanks Andy, I'd been thinking about replacing the injectors anyway as I can't find anything in the service history to suggest they have ever been replaced before. Another possibility is the cold start injector I guess?

 

[stever]

Update to an old thread.

I replaced the injectors, which improved the situation a little. The breakthrough came by chance - a fuel leak required the replacement of two rubber fuel pipes at the bottom of the tank - problem solved! I guess pressure was being lost from vapour/ fuel escaping out of the pipe, between the accumulator and the engine.