My neighbor's 1984 190D 115K sometimes runs weak from start (as if the engine is starved for fuel). The problem does not go away as it warms up. The car must be shut off and re-started. It may run weak again, or not. When it does start and run with normal power (most of the time) it continues to run normally until it is shut off.

I thought it sounded like a fuel pump relay not functioning properly every time, or maybe a fuel stop valve sticking closed (or partially closed).

Any ideas?

Have you checked the linkages from the accelerator pedal to the fuel injection pump? Maybe a bushing of some sort has worn or some of the linkages are binding at times, thus the intermittent lack of power.

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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

The linkage looks OK, and once the car starts normally, you can drive it for hundreds of miles with (apparently) normal power and normal linkage function.

thanks for the idea.

I'm sorry, SW, I mis-stated the problem. The weak running is only intermittent in the sense that it does not always happen. When the problem does occur, it happens thus: You start the car, it is sluggish to start and runs poorly; it will not develop power. The weak running does not go away until the engine is shut off. When the car is re-started, it may run normally. If it does run normally, it continues to do so until the engine if shut off.

The problem always appears upon starting and does not go away until the engine is shut off and re-started.

Hope that helps.

If the fuel filters have not been replaced annually, this would be a probable cause. Especially since you stated that in addition to being sluggish, it runs poorly.

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1980 Mercedes 240D
1982 Mercedes 300SD
1985 Mercedes 300D
1993 Dodge Cummins Turbo Diesel

My neighbor is pretty careful about regular maintenance including changing fuel filters.

We don't think air is likely the problem, since after a few re-starts, it will start normally and run fine all day long.

This problem can not be caused by a fuel filter; if it was a filter problem, the car would not run good after restarting. A fuel filter problem does not only occur upon starting.
What is the exact problem: does the car start at a lower rpm as normal? or is it impossible to accelerate normal after starting? or does the car start on one cylinder less?

If the car starts on a lower rpm level as normal, but runs fairly good when accelerating, it is a vacuum problem. The 190D has got an vacuum pod to provide a higher rpm when the engine is cold.

If the car occasionally starts on one cylinder less as normal there is probably one glow-plug going bad.

If the car does not accelerate as normal, but only with half power, the problem can probably be found in the fuel-pump. However, if it is a fuel-pump problem it should occur on a regularly base and not just now and then. The fuel-pump on a 190D is completely mechanical driven and therefore is good or is bad and will not be bad just now and then. The later C-class diesel with the electrical driven fuel-pumps suffer this problem a lot. The C200D is rather good, the C220D needs a new fuel-pump every (approx.) 200.000km and the C250D occasionally has a fuel-pump problem...(but the fuel-pumps on the C220D and C250D are electrical driven).

Personally I think you have to find the solution to this problem in the vacuum system, since it does not occur on a regular base. All the other parts on the engine of the 190D are mechanical and are either good or bad...

greetingz,

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1990 300SL-24
1993 C250D with a minor 600+k kilometer
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