Author Topic: Another 6.9 that wont raise (diagnostic tips)  (Read 1215 times)

secondslc

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Re: Another 6.9 that wont raise (diagnostic tips)
« Reply #45 on: 21 June 2020, 03:09 PM »
Awesome, thank you so much for the guidance.

The pump, the injectors, the distributor, and the lines to all that are new. What is still suspect is the WUR, Idle Valve, Accumulator, and CSI.

Im suspecting the WUR is the biggest culprit. Do I buy a new one, get one from CIS flow tech, or go with the one from unwired?

And yeah, im good at shot gunning and replacing it all so I know its new fresh and tunable, its just right now...im still trying to understand what it all does.

Again, the WUR...the bane of my existence I think..
1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

daantjie

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Re: Another 6.9 that wont raise (diagnostic tips)
« Reply #46 on: 21 June 2020, 07:23 PM »
I would not flip out the WUR just yet, pressure tests first to see what is what.

Also, you will see a can - type fuel pressure regulator at the back of the fuel distributor (fire wall side), plumbed into the fuel lines.  I recall vaguely a member having issues with these a long time ago, and changing it out solved their issue though I cannot recall what the problem was.  They have a diaphragm inside which can go bust, especially if it's original to the car I would replace that as well.

Here is a pic:

« Last Edit: 21 June 2020, 07:35 PM by daantjie »
Daniel
1977 450 SEL 6.9 - Astralsilber

secondslc

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Re: Another 6.9 that wont raise (diagnostic tips)
« Reply #47 on: 22 June 2020, 04:48 AM »
The damper was replaced too... funny enough, i had the car idling but it would shut off on throttle.

Turns out it was leaking into the vacuum system just enough for the car to run and hide the fact that all 8 injectors were clogged. I replaced that and then it would no longer start... which led to more parts getting replaced...
1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

daantjie

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Re: Another 6.9 that wont raise (diagnostic tips)
« Reply #48 on: 22 June 2020, 08:58 AM »
Sounds like "whack a mole", fuel pressure test should make things clearer I would think.
Daniel
1977 450 SEL 6.9 - Astralsilber