In a message dated 1/30/2006 11:48:28 A.M. US Mountain Standard Time,  

My SD  has it's moments of fuel pressure loss.  You can be crusing down the  
interstate and suddenly feel a power loss that lasts less than 1/2  
second...something exactly like taking your foot off and back on the  throttle. 
at cold start it's very rough and needs to have enough  throttle to keep at 
least 800-900 RPM to run somewhat smooth and not  die.  Glow plugs are barely 2 
years old and the injector pump and  injectors were replaced by the P/O (maybe 
50kmi ago).  I've replaced all  the rubber fuel line from tank to primer in 
the last 8 months.
I'm thinking  from my experience in the semi-diesel world that I have a lift 
pump that's  weak.  I read 07.1-145 "Checking fuel pump and bypass valve" and 
it seems  that the bypass valve can get clogged and needs to be cleaned and 
the spring  lengthened to increase tension.  Is there anyone else that has had 
an  issue similar to this where cleaning the bypass valve fixed the issue or 
did  they have to replace the fuel pump?

Don't overlook the possibility that it is the boost protection switch,  
mounted on the intake manifold.  These will go bad and cut fuel just as you  
describe but at only 6 or 7 psi instead of 14-15 psi.   When the  switch closes 
interrupts the pressure signal to the ALDA and the engine gets  fuel, the 
equivalent of an unblown car, which feels fairly anemic 
You can pull the wire from the switch to see if your problem goes  away.  Or 
you can remove it and rig a test connection with your mitevac or  air 
compressor.  Or a remote possibility is the turbo unloader valve  is failing 
and the 
pressure is excessive.  
Good luck,   

Jim  Friesen
Phoenix AZ
79 300SD, 262 K miles 
98 ML 320, 140 K  miles

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