Topic: K-jetronic pressure testing (troubleshooting)

[daantjie]

Looking at the bottom of this tank screen I would say you have a "rust - o - rama" in that tank of yours

[raueda1]

Looking at the bottom of this tank screen I would say you have a "rust - o - rama" in that tank of yours

Sure enough.   More strongly than ever, based on this long adventure and that of countless others (including myself), I'm convinced that there's really just one way to deal with these old cars:  Remove, test &/or replace everything related to fuel, starting at the rear.  Just fixing/rebuilding/replacing one element is almost never enough, and it will just reveal a problem someplace else. 

Remain calm and carry on!

[Big Tiny]

Yes tank screen is terrible.

No point even attempting anything else until this is fixed.

[Jan S]

Borescope inspection tomorrow. Sleepless nights in front of me? We'll see ......

I cleaned the bracket today. I have ordered all the parts including new rubber buffers, bolts, washers, pump, filter, accumulator, hoses, strainer ....... everything.

[Jan S]

Put the borescope inspection on hold, unfortunately - the equipment I borrowed was not EX-certified. Risk is too high. Shit can happen .......

I will probably go for this inline filter between tank and pump inlet, it's 14 mm or probably 9/16". Perfect for the hose.

https://mercedessource.com/store/1978-1985-bosch-gasoline-fuel-pump-protection-pre-filter

[Jan S]

Things are moving slowly forward. Waiting for parts for the fuel system.

Yesterday I removed all fuel hoses in the engine bay. New ones will be SAE J30 R9 standard.

I have a non-original engine, and for some reason the previous owner has cut the metal fuel line between Fuel distributor/pressure damper and warm-up regulator and connected them with a 8 mm fuel hose with length 9 cm.

Inside the metal line one can see a hard-plastic hose.

- does anybody know the purpose of this hard plastic hose?
- what is the consequences of both the metal line and hard plastic hose being cut? Fuel will probably end up between the metal line and hard plastic hose along the entire length of the line .....

I might have to buy a new one .....

[Jan S]

See pic

[daantjie]

I am not clear what you mean, do you mean you now have a non - metal line running between the WUR and FD?  And then the cut metal pipe you show is what the previous owner did?  As far as I know that metal line has a sort of "baffle" inside.  This metal line is no longer available, and they are notorious for shearing off at the WUR because the line thins out a lot at the connector, so if it's rusty as is often the case most folks unfortunately shear off the line in an affort to remove the connector at the WUR.

[Jan S]

I still have the metal line between FD and WUR, but a piece in the middle - approx 20-30 mm long - has been cut out (see pic). Hence the previous owner put in a fuel hose and two clamps to connect those two ends.

Inside the metal line you see a hard-plastic hose. Is that what you call a baffle?

[Jan S]

... somehow I struggle posting pics .... an error occurs ....

[daantjie]

Inside the metal line you see a hard-plastic hose. Is that what you call a baffle?

Yes that would be the baffle.

[Jan S]

Do you know the purpose of the baffle?

Any consequences of both the metal line and the baffle being cut?

[daantjie]

Do you know the purpose of the baffle?

Any consequences of both the metal line and the baffle being cut?

Not sure really.  Perhaps to smooth out pressure variation in the line

[raueda1]

Do you know the purpose of the baffle?

Any consequences of both the metal line and the baffle being cut?

More pictures would help, to be sure.  I'm having hard time visualizing what's what.  Regardless, just curious, what year is the engine?  And what's the orientation of the WUR?  Most seem to face upwards, though some early ones (like mine) face sideways.  Significantly, the  fuel line constructions for the different WUR orientations aren't the same.  One of mine is nylon with a thick RUBBER sheath on the outside.  I  can't remember which one and car is in storage so I can't look.  But that line corresponds to your tube-inside-metal version. Maybe the tube-inside-metal version is just an upgrade from what I have.  I've wondered why one WUR line is so thick on the newer cars.  Maybe a fire precaution?  But then why the tube, not just metal?  This all seems to support the baffle idea.  But maybe we'll never know.  It's amazing to me how many dampers, baffles, etc there are on these cars.  Clearly there are lots of things going on that I can't comprehend.

Anyway, based on all that it seems like the tubing is there for some purpose.  Just connecting the metal tubing by splicing in fuel hose would seem to defeat that purpose. Under the circumstances I think I'd try to fashion a proper replacement for the whole thing.  Or, better still, find the real part someplace.  Good luck.  Eventually all this will get solved!  Cheers,

[Jan S]

Thanks to both of you for your assessment.

Engine is 100.985 (6.9), US version, left the production facility 7 Nov 1977. I will post a pic to show the WUR orientation.

Yes, I will try to find a used one. Won't be easy. At least fix properly.

1-2 weeks before I can assemble the new fuel system, hopefully (still waiting for some parts).