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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 54028
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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Could you offer any advice on what to check with this

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Could you offer any advice on what to check with this situation? Video is at the link provided.
Customer: replied 27 days ago.
Even with the Frequency Valve removed after sometime the car will stall out. I just go finished running a can of intake clear through the throttle body and had a great reaction out of the engine. It was running well, responding quick to gas pedal, and blowing out all kinds of yuck. Once the exhaust cleared up, I took a loop around the parking lot (about 300') and it stalled pulling back in the drive and will not stay running now.

Hi, my name is***** fuel pressure gauge is connected to the wrong ports. You need to connect the gauge to the line that goes from the top center port of the fuel distributor to the warm up regulator. More than likely you have a bad warm up regulator. You should measure about 3 bar on that line when the car is hot and the gauge is open.

Customer: replied 26 days ago.
Video with correct connection, still same problem when I reconnect the Frequency Valve.

Have you tried adjusting the mixture a little richer? Will it run well if you leave the frequency valve disconnected?

Customer: replied 26 days ago.
With the valve disconnected it will run more often, but still stalls out. Once it sits for some time (an hour or so) this process starts all over again. It will start up, idle good, able to rev up if you do it slowly. If you try quick acceleration on the throttle it will stall out, but you can ease into it and it will rev through. But, after some time, 3-4 minutes you are back to the stalling and it has to sit for a cool down period. It seems like it is a temperature response since it restarts the process once cooled down a bit.

Even though you have good fuel pressure you may have poor fuel flow (volume). Have you checked the fuel tank for rust. It sounds like it may be starving for fuel after it runs awhile.

Customer: replied 26 days ago.
But what relevance would that have with the frequency valve connection stalling it out? I could check the fuel in the tank again or possibly draw the fuel from a gas can to eliminate the chance of it being the tank. I have replaced the backend fuel components(pump and filter) already after the tank was drained and refilled. Perhaps I could purchase new filter and cut the old one in half to see the collection on the media inside? If there is indeed a bulk of material in the filter then that would explain the starvation of fuel, correct? Are there other screens in particular that should be checked as well for debris from the tank? I just went out and restarted it again after sitting for 2 hours, no start with FV connection until mix screw was almost all the way out, then it would stumble and stall. Unplugged the FV, started right up and was able to screw down the mix until about a turn and a half before seated. Was idling well when I had just gotten your latest message.

I thought it acted the same way with the valve connected or disconnected. When you connect the valve you are changing the mixture. If the fuel flow is low it could be worse with the valve connected. There is a screen that screws into the bottom of the fuel tank. If the screen is plugged with rust from inside the tank it can act this way.

Marty and 2 other Mercedes Specialists are ready to help you
Customer: replied 26 days ago.
Ok, I will check that. Thanks for all your assistance Marty, I really think I have gotten in over my head with this car. Older is not always simpler as I am finding with this car.

You're quite welcome.