123 Chassis - 240D problems

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Doug - 05 Jul 2007 07:25 GMT

My 1977 240D won't sustain a low speed idle. By that I mean that once
started, the revs constantly increase until the engine is roaring.
The car can only be driven by downshifting the 4 speed manual, forcing
down the engine rpm's while also braking. An ungood condition!

The car also won't shut off. For that I suspect the vacuum diaphragm
in the fuel injection pump. Are the problems interrelated?

The vacuum pump seems to be working since the power brakes are normal.
There is no locking system so door vacuum lines, etc are non-existent.

From an aftermarket tech manual I see that there are two types of
mechanical fuel pumps. One has a mechanical governor, the other type
is pneumatic. Should I start my investigation there?

tnx,

Doug

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-->> T.G. Lambach <<-- - 05 Jul 2007 16:45 GMT

Look at the simple stuff first.

Check the throttle linkage to ensure it returns to its idle stop screw
limit.

Replace the "shut down device" (Vacuum bellows that pulls the fuel rack
to OFF when you turn the key to OFF). These cost about $35 on line.
Then, it will either be fixed or you know the shut down is excluded from
further consideration.

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Doug - 06 Jul 2007 07:03 GMT

>Look at the simple stuff first.
>
[quoted text clipped - 5 lines]
>Then, it will either be fixed or you know the shut down is excluded from
>further consideration.

Thanks for the hints.
I had already checked the external stuff like making sure that the
linkage returned to its stop. The engine starts racing WHILE the
linkage is at the full stop postion.

I'll order that bellows.

Doug

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