have a 1982 300D which has started stalling only when I am driving about 5 to 15 miles per hour. Never when standing still. This morning it quit 2 times driving to work always when coasting after letting off the fuel pedal. I coast to a stop and it will restart instantly. I think the idle speed might be to slow, the valves have been adjusted and fuel filters replaced, any ideas?
Thanks, Nick

Air in the prefilter?

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1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Yes look for a small stream of bubbles entering and going through the prefilter. There is always one pretty consistant bubble in there. Ignore that.
If your primer pump tends to leak you may want to consider upgrading that as well. That can be a common air leak into the system.

check and lube the linkages too. they might be getting stuck in a position where the engine is not getting enough fuel to compensate for the load.

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2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
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'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

barry123400,

What can be done to upgrade the primer pump? Im new to the Mercedes cars. I have a 1976 300D that runs great, but will die when letting off of the "gas" pedal at 45 mph or higher. I suspect the primer pump to be the letting air in but have not tested for this or know how yet. Any help would be great!

Thanks,
Keith

76 should have an idle speed control knob on the dash that should enable you to turn the idle up and resolve that problem.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Kerry, you are correct about the idle knob on the dash BUT, the car will die if I let off the "gas" pedal while going down the high way. This still happens when the idle is turned very high. When the engine is sitting at an idle, I can hit the gas pedal and the engine will engine will die. I guess this is a good time to say the engine has never cut off with the key since I have had it. Any other suggestions?

Thanks,
Keith

Have you replaced the fuel filters and checked the fuel strainer in the tank?

Also is the a "whoosh" sound when you remove the fuel cap?

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Firstly, did this problem start immediately after you performed any sort of maintenance procedure? If so, determine what you may have done incorrectly.

Otherwise, the idle speed should be around 750 rpm. Before I adjusted the idle speed (on the injection pump), my car would stall if I completely let my foot off the accelerator in cold weather (when the engine was cold).

Also, have you checked the strainer at the bottom of the fuel tank? If this is plugged, your flow of fuel may be impaired. I suggest setting up a mini fuel tank (as done in diesel purge on dieselgiant.com) to rule out an issue with the flow of fuel. If the vehicle continues to stall, you know that the fuel system is not the cause. What does the air filter look like? (granted, it would have to be very dirty to cause the engine to stall)

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Vehicles Owned:
1983 Mercedes Benz 300D ~ 212,000 miles
2005 Mazda 3 S ~ 96,000 miles