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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53901
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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1987 300e stalling. Changed voltage regulator, Over Voltage

Customer Question

1987 300e stalling. Changed voltage regulator, Over Voltage Relay and Fuel Pump Relay still stalls?? Please help
Submitted: 9 months ago.
Category: Mercedes
Expert:  Marty replied 9 months ago.

Hi, my name is***** common cause of stalling on this model is a bad distributor cap and rotor or a bad ignition coil or crankshaft position sensor. Another possibility would be a bad idle control valve. I need more information from you in order to point you in the right direction. What happens after it stalls? Does it start right back up? If you keep your foot on the gas pedal and raise the rpm a little bit will it still stall?

Customer: replied 9 months ago.
I also cleaned the idle control valve and drove with the Idle control valve disconnected. It ran fine like it usually does for about 20 minutes and started stalling again. Same if I had the Idle control connected or not?? If I wait after stalling it will cool off and run again for 20 min and start stalling again. The engine is not running hot. Does not seem to stall when pressing on the gas, mainly when I let off the gas and slowing down. Wish I knew what to do?? Please help.
Expert:  Marty replied 9 months ago.

If you cannot start the car for 20 minutes after it stalls you need to test for spark and test the fuel pressure when it won't start. You can also remove the air cleaner and spray a little ether into the air intake while a helper cranks the motor and see if it will fire or will run on the ether. If it does it would indicate a fuel problem and not an ignition problem.

Customer: replied 9 months ago.
it makes more since, it will start after it stalls but will have hard time to re-start and will stall again quickly thereafter??
Customer: replied 9 months ago.
I have been reading more about the crankshaft position sensor; would that stall the vehicle while running? Thanks
Expert:  Marty replied 9 months ago.

If it tries to start after it stalls it sounds like you are losing fuel pressure. If the crank sensor was the problem it would crank but not even try to start at all since there would be no spark.

Customer: replied 8 months ago.
Hi Marty, Here is where I am at, we got the car to stall again and use ether and it started rough and would stall when ether stopped. Next we let it cool off and started right up again, jumped the fuel pump and let it run and it stalled again, even though we could hear the fuel pump running. Again it is the same thing we can let sit and start cold and it will run for a 20 min and then it just stops and stalls. Let it sit for a few minutes and partial cools and it will run maybe a couple of minutes and stall again. If you try and start right after it stalls it will not want to do much of anything, maybe a sputter. It just seems there is a safety switch or something after the car warms up that switches and is malfunctioning at that point. Any ideas, please help?? Another blog mentioned vacuum leaks??
Expert:  Marty replied 8 months ago.

It sounds to me like either the fuel pump is getting hot and losing pressure or you are getting low flow out of the fuel tank to the pump. There is a screen in the tank that can plug up and restrict the flow. It won't be vacuum leaks and since the car will run with the ether it tells you that the ignition system is working. I'd focus on the pump and the fuel flow. You should also check the fuel filter.