Starting problem 91 300GE
 

Hi guys, I have a strange problem with my 1991 300GE (3.0 litre 12 valve M103 with cat convertor, same as W124 300E or W126 300SE) 180.000 kms. When the car is not fully warmed up and I try to restart it shortly after shuting the engine down (e.g. after taking fuel), it won`t start again, the engine just turns but does not fire. If I wait about 5 minutes it starts without problems, if I help the car with the gas pedal I am able to start it after about 3 minutes. I have also noticed the very first morning cold start is quite difficult in colder weather, it sometimes takes 2 or 3 tries.

Any idea? Thx in advance.

Welcome
How long since you changed your cap and rotor ?
How old is the fuel filter ?

October 2013, so about 2 years and 20.000 km ago.

Have you checked the fuel pressure at the large inlet line ? Good to cover it before you crack it loose. Should spray fuel to the inside of the hood (bonnet)

Have you checked for vacuum leaks ? Just about any spray will work. Dont forget to check your injector boots.

Morning start issue... check your cold start injector.

It's the forum cliché I know but the OVP relay is worth looking at in this situation. When an OVP is bad the engine relies on its base settings which are typically tuned to warm engine running.

crank position sensor
 

You problem sounds exactly like the problem I had with my 1991 300SL. It would run fine and then after parking the car for a few minutes, it would suddenly not want to start again until I waited 5-10 mins then it would run. It turned out to be a lose crankshaft position sensor. Search for my post on the subject. Remove, inspect, clean, and re=install the sensor. Better yet, if it's a very old one replace it. Hope this solves it.