Does anybody know where the fuel bypass valve (the one that controls fuel feed pressure to the IP) is located? Also, is this valve adjustable? Help would be greatly appreciated. Thanks.

What engine?

the engine is a 617.952 (1984 300TD)

sooo... anybody know where this thing is, how to remove it if it needs removing, how to ramp up the spring pressure, etc???

I think you'll find there is no 'Pressure control Valve'.
The system pumps against a metered orifice on the outlet of the fuel filter and dumps fuel back to tank via this .
VW and Volvo, Bosch diesel systems use the same orifice type pressure control.

You should find this hollow bolt on the filter head and on VW and Volvo on top of the i/p. The later is stamped, 'OUT'.

If there is one, I have never found it....although I must admit, I've never looked for one, being as I understood the above to be corrrect.






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http://mb.braingears.com/123_DISK2/program/Engine/617/07_1-145.pdf

go to that link, download the file. you will see a very clear drawing of a pressure-relief bypass valve. So, I am fairly certain there is one, I just would like to know where it is.

Okay...learn something every day

Look on i/p at banjo bolt on engine side of i/p between #4 and #5 elements on i/p........it contains the refered to pressure regulating spring/ball check assembly.
You'll have to remove the injection lines to get to it.


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__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."