Author Topic: Exact fuel pressure test hookup help needed for a California 6.9  (Read 1089 times)

raueda1

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #15 on: 01 September 2020, 09:04 PM »
It's pretty clear that the o-ring pictured is destroyed.  Progress!!  Replace it.  There's also an o-ring on the regulator piston.  The large spring goes into that but it often stays behind in the FD when removing the regulator.  Get a stiff wire and insert into the bore and you should be able to fish it out.   Be careful, obviously you don't want to scratch the bore.  If it doesn't come out easily then you've identified a problem.  There's an o-ring on that too and it should be checked or simply replaced. 

If the regulator doesn't have any small washers on the shaft then yes, it's missing parts.  They go between the larger spring and the regulator shaft.  See this:
https://www.autohausaz.com/pn/11949622-F026T03010?utm_source=google&utm_medium=cpc&utm_campaign=feed_Mercedes&gclid=EAIaIQobChMI_eb-5snJ6wIVOx-tBh2ZhwcOEAQYASABEgL8UPD_BwE and this: http://www.bosch-classic.com/en/internet/bosch_classic/produkte/motor_1/systemdruckregler_1/systemdruckregler___mit_teaser_1.html
  All those washers are used to set the pressure.  If you don't have them just buy one of these kits.  I don't think washers are available individually.  Keep the progress, info and pix coming!  Cheers,
« Last Edit: 01 September 2020, 09:14 PM by raueda1 »
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

raueda1

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #16 on: 01 September 2020, 09:20 PM »
and just a small anecdote about how screwy this stuff can be.....    My car had a malfunctioning WUR.  Rather than fixing the WUR somebody fiddled with the system pressure until they got it down to the control pressure.  The car ran but the WUR wasn't really doing anything.  Of course starting was hard, idle sucked etc etc.  Point is, never assume.  There seem to be a lot of people out there that take short cuts or have no idea.  Just highlights the importance of starting at the beginning.
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

secondslc

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #17 on: 02 September 2020, 05:00 AM »
I have washers/shims, but i guess i have to dig in and get the rest of the regulator out.

Anybody have o ring specs?
1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

raueda1

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #18 on: 02 September 2020, 09:30 AM »
I have washers/shims, but i guess i have to dig in and get 1. the rest of the regulator out.

Anybody have 2. o ring specs?
1.  It's just that small piston and will take about 3 seconds once you know it's there.  It's not tight.  OTOH, if it IS tight then...    :o

2. Sadly I do not and can't recall ever seeing them  I think most folks just buy the kit.  You could measure but maybe let the rings sit for a week or so (preferably in a vacuum oven, haha, cause we all have vacuum ovens sitting around, right?) for fuel to diffuse out so rings aren't swollen by fuel. 
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

secondslc

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #19 on: 04 September 2020, 02:02 PM »
30 second test gave me more than a liter... but boy do i need better gas

Next step?
1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

secondslc

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #20 on: 04 September 2020, 05:07 PM »

Yeah, the piston is JAMMED in tight. I don't know how it can come out without ruining the bore....

I'm going to go to NAPA tomorrow and ask if they have ideas, otherwise I have a spare unrebuilt aluminum FD I can throw on... But I really liked the cast iron one...

Ugh

1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

secondslc

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #21 on: 04 September 2020, 06:28 PM »
Im just going to get a new FD, the aluminum one is used and the control plunger does not move freely.

Other than the gross fuel thats sitting in the car, everything will be new fuel system wise, and well... its easier to diagnose and tune at that point.
1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

daantjie

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #22 on: 04 September 2020, 08:07 PM »

Yeah, the piston is JAMMED in tight. I don't know how it can come out without ruining the bore....

I'm going to go to NAPA tomorrow and ask if they have ideas, otherwise I have a spare unrebuilt aluminum FD I can throw on... But I really liked the cast iron one...

Ugh

Maybe try some heat if the FD is off the car.  Localized heat from a propane torch can work wonders.  Safety first of course.  Could just be some gummed up fuel keeping it stuck.
Daniel
1977 450 SEL 6.9 - Astralsilber

secondslc

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #23 on: 04 September 2020, 08:12 PM »
I’ll do this outside and what have i got to lose lol
1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

raueda1

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #24 on: 04 September 2020, 08:43 PM »

Yeah, the piston is JAMMED in tight. I don't know how it can come out without ruining the bore....

I'm going to go to NAPA tomorrow and ask if they have ideas, otherwise I have a spare unrebuilt aluminum FD I can throw on... But I really liked the cast iron one...

Ugh

Maybe try some heat if the FD is off the car.  Localized heat from a propane torch can work wonders.  Safety first of course.  Could just be some gummed up fuel keeping it stuck.
Careful though!  Too much heat would likely damage the miniscule filters under the lines going to the injectors.  Another possibiulity might be to shoot freeze spray inside the bore to shrink the cylinder after a good penetrant soak.  Kind of mirror image of heating.  It's worked for me before.

Secondslc:  There is a silver lining here - if that cylinder is jammed you now know at least one sure cause of your crazy pressure There may be others too, but if that piston is stuck it's go-to-jail-do-not-pass-go!  You might just want to go ahead and rebuild the iron FD.  B ut if you go with the AL version note that the aluminum FD's have adjustment valves for each injector.  Don't mess with them!  Also, I'm pretty sure that  lines and fittings are different.  Not much maybe, enough to make installation very annoying.  I'd discuss with CIS Flowtech and describe the problem and see what they think.  Yeah, obviously you'll want new gas....    Cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

secondslc

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #25 on: 04 September 2020, 09:01 PM »
I’ll get some freeze spray and a torch and play thermodynamics tomorrow
1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

raueda1

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #26 on: 04 September 2020, 10:22 PM »
Is the FD still on the car?  Maybe remove it to do this stuff.  The fuel lines should come off easily enough and then it's just 3 screws.  Then no fire risk.

 Also, with all the fuel lines off you can rescue the tiny filters directly under the line couplings in case of too much heat. They should come out easily with a very fine wire. 

If you take the FD off be VERY careful not to drop the central plunger.  It can easily fall out.  Then remember to put it back, as I learned the hard way.
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

secondslc

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #27 on: 05 September 2020, 06:41 AM »
Its been removed, I plan on only heating the pressure regulator section (may just use a heat gun) and then spraying the piston with freeze spray. It should give me the best chance
1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

secondslc

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #28 on: 05 September 2020, 10:23 AM »
Freeze spray to the rescue... now... what size are the dang o rings
« Last Edit: 05 September 2020, 03:06 PM by secondslc »
1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8

secondslc

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Re: Exact fuel pressure test hookup help needed for a California 6.9
« Reply #29 on: 05 September 2020, 03:06 PM »
A good update..of sorts

 Got new o-rings, and put it all together. Was able to adjust the fuel trim screw to where the fuel in the FD was not going up or down when the injectors lines were unhooked as per:
https://k-jet.biz/fuel-distributors/


-System Pressure is ~5.4 Bar
-With the fuel pump running... opening the valve, I get half a bar.
-Shutting the system off, the pressure shoots up to 2.4 bar or so, and then in 20 seconds drops to zero.

Is my accumulator busted?

1979 6.9
1983 urQuattro
1991 200 20V Avant
1993 Corrado SLC
1996 SL600
2009 Super V8