Engine stalling when accelerating ... Pierburg 2E-E

[msejensen]

Hello, I have some problems with my Mercedes 190 2.0 1988 with Pierburg 2E-E carburator.

1. When I try to accelerate the engine stalls for a few seconds. Then all of sudden it accelerates. The behavior is worse when engine is cold and at low RPMs. When the engine is warm it it doesn't stall, but it will hesitate as I press the accelerator. The behavior is only present under load, doing the same thing with clutch down will not show any problems, it will gladly rev.

2. When driving on the highway at constant speed the engine will gradually lose power over a time of some few seconds. Then all of a sudden it will snap back with full (normal/expected) power. Then after a few seconds it will gradually start to loose power again. It will then go on like this and repeat the cycle.

I suspect the second issue is related to the first, but I have no clue what the problem may be. I would greatly appreciate any help.

Regards

 

[television]

Hello and welcome, your fault could be fuel starvation, blocked fuel filter or poor pump.

Välkommen

See what others think

 

[Number_Cruncher]

1) Check the ignition HT system

2) Check that the cold / warm air intake is working properly

 

[MechPhil]

Make sure you don't have any air leaks (vacuum leaks in other words) anywhere between the carb and the engine. This could be at the faces between the carb and the manifold or between the manifold and the head, or on vacuum hoses, of which there are hundreds. But an air leak would cause a stumbling idle (called hunting, the engine speed cycles between very low and well above idle a couple of times a minute)

The other thing to check is the accelerator pump. That's the pump that squirts fuel into the throat of the carb when the throttle is opened. The acc pump is most often the cause of the stalling you describe.

As for the fluctuation in power at constant speed, I have an idea that that may also be from the carburettor, from the power valve.

The acc pump diaphragm is numbered "G" on the diagram below. It should pump a squirt of fuel through the unnumbered little pipe in the top of the smaller venturi while the throttle is opened.