[EMAIL PROTECTED] wrote:
In a message dated 1/30/2006 11:48:28 A.M. US Mountain Standard Time,
[EMAIL PROTECTED] writes:
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. Also,
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?
Luther,
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 it
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.
Unlike when the wastegate opens to limit further boost and power, when
the overboost switch activates, power instantly drops about 30% (but the
engine should NOT stall - there should be sufficient fuel to allow the
engine to run at about 70% of full power). Check this by disconnecting
the electric line to the switchover valve of bypass the pressure line
thru the switchover valve (directly from the intake manifold to the
ALDA). Vacuum in the tank can choke off fuel/power and may even cause
the engine to stall, but simply opening (and then reclosing) the gas cap
and letting air rush in, restores fuel flow (at least for many miles).
This tends to happen unpredictably but usually only after you've been
driving for a while.
Marshall
--
Marshall Booth (who doesn't respond to unsigned questions)
"der Dieseling Doktor" [EMAIL PROTECTED]
'87 300TD 182Kmi, '84 190D 2.2 229Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5
turbo 237kmi
