My Dad's '91 190E 2.3 has a warm start problem. Here's the scenario.
First start of the day, the car starts easily (crank for 1 to 2 seconds) and runs fine. After completely warm, if the engine is shut off and started within 30 minutes, it starts fine. If the car sits for between 30 minutes and 4 hours it requires 5 to 10 seconds of cranking and then it catches and idles poorly for several seconds before smoothing out. After which, it runs fine.
What's been done by an indy: new injectors and rebuilt fuel distributor. Didn't make any difference. They claim to have run diagnostics on all the sensors, fuel pressure, and OVP.
Now, two strange events:
I took the car to the dealer for diagnostics. They kept it for two days and could not find anything wrong with it. They claimed it started fine every time and they tried it at many different intervals. When I picked up the car, it started right up. The next day, I tried it and it behaved perfectly. The day after that, it exibited the same hard start condition I mention above.
On a whim, I ordered and installed a new fuel accumulator. For three days the car started perfectly all the time. Then it was back to misbehaving.
Any ideas??? Fuel pressure regulator?