car starts but wont run

I have a mercedes 190e ( 1992 ) manual saloon. It starts at very high revs for approx 10seconds Then the engine dies, a mechanic friend has looked at the problem but cannot find the fault. He thinks it is an electrical problem. I would be grateful for any suggestions Regards Duce

Again, I would start out by checking the fuel pump relay... make sure it is not original to the car.

Sounds like a massive vacuum leak. FI or carb engine? Look for a broken brake booster vacuum line.

Motor is running on the extra fuel from the cold start injector or choke PLUS the vacuum leak that Karl cited.

It quits after 10 seconds because that's when the "extra" fuel from the cold start system stops being fed into the motor.

Without that extra fuel the vacuum leak snuffs the motor. That vacuum leak, plus the extra cold start fuel, accounts for the high rpms.