Fuel lines on a w126 - PeachParts Mercedes-Benz Forum

Monomer · #1 08-25-2006, 06:34 PM

I'm a bit confused.

theirs a total of three lines running from the back. One of which I can identify as the send - it go's straight to the fuel distributer. Another line also hook into the distributer, but get sidetracked into what looks like an AC line.

Is this MB's way of cooling fuel?

Here's what I'm trying to do: I broke all three lines (in various place) that run right by the driver side wheelwell. It seems as if the rubber bushings hold in water, because every line that touched one is rusted - and most rusted through. So right now I'm "patching" everything. I noticed these lines run right nextto the exaust manifold, which is a shame because I cant be cheap and splice a rubber line in (which I did before noticing it's placement) I'm going to insulate it with fiberglass, no worries.

PS the bushing have to be a design flaw. I suggest spraying them with a rust-inhibiting paint (POR15) and then covering with spray body undercoating. this is NOT fun.

dpetryk · #2 08-26-2006, 08:55 AM

Short answer - Yes. That thing you refer to is used to cool the fuel returning to the tank. They do this because the fuel tank contents would be gradually be heated up since it circulates through the hot fuel distributor then back to the tank.

david s poole · #3 08-26-2006, 11:55 AM

one line is supply,another is return and the third is fumes from the tank to the charcoal cannister and yes the fuel cooler does exactly that.25 yrs ago i used that idea for an intercooler on a turbo 280zx-worked like a charm.

Monomer · #4 08-26-2006, 11:57 AM

Quote:

Originally Posted by dpetryk

Short answer - Yes. That thing you refer to is used to cool the fuel returning to the tank. They do this because the fuel tank contents would be gradually be heated up since it circulates through the hot fuel distributor then back to the tank.

ahhh, much like a vein pump heats oil up.

What kinda of pressure are we talking about here - The hose I bought is rated at 50PSI.

dpetryk · #5 08-27-2006, 08:23 AM

90 psi on the supply side almost nothing on the return side.

Monomer · #6 08-27-2006, 02:06 PM

Quote:

Originally Posted by dpetryk

90 psi on the supply side almost nothing on the return side.

The hose is holding up on all sides, I'm just wondering now if I have everything plumbed to the right place - she wont start right now.

Is there something I'm missing? A procedure to "bleed" the fuel lines of any air?

The Hoses are inplace of rusted through lines. What I did was flare the end of the pipe and connect the hose with the proper clamps. 90 PSI sounds about right, As I've been troubleshooting some small leeks. Does anyone by chance have a schematic of the fuel lines? (More specifically, the ones that run right into the fuel distributer)

Monomer · #7 08-29-2006, 11:05 PM

Can someone please Identify the two lines in the second pic.

I'm afraid I have lines crossed, And need to double check. I cant trace them that far back because the diff is in the way.

Monomer · #8 08-31-2006, 10:42 AM

Anyone?

Can someone atleast tell me which hose is the supply side on the Bosch KE-Jetronic distributer?

I REALLY dont want to hook this up wrong.

dpetryk · #9 08-31-2006, 10:59 AM

The one that comes from the fuel pump. Turn the key on and fuel should come out of only one of the lines. That will be the fuel supply line.

Monomer · #10 08-31-2006, 04:04 PM

Quote:

Originally Posted by dpetryk

The one that comes from the fuel pump. Turn the key on and fuel should come out of only one of the lines. That will be the fuel supply line.

yeah, but whats the "in" on the fuel distributer?

I know it's under pressure - TRUST me; I KNOW.

dpetryk · #11 08-31-2006, 04:19 PM

The supply line goes directly into the fuel distributor. The return from the distributor goes to the pressure regulator then to the fuel cooler then to the return line to the tank. So look at the lines and trace them out.

Monomer · #12 08-31-2006, 05:33 PM

She Starts!

now, what to do about the black smoke....

Monomer · #13 08-31-2006, 09:15 PM

I spoke a bit to soon.

It ran REALLY rich, and then decided not to start at all. With the key in the second position, you can hear the fuel pump cranking as normal, and the frequency valve ticking. It's not getting any gas to the injectors lines (cracking one open, I saw no fuel)

Do these things need to be blead?

david s poole · #14 09-01-2006, 12:23 PM

you prbably have stuck piston in fuel distrib.pull out your fuel pump relay and jump it to keep the pump running and tap on top of fuel distrib while fuel running.

Monomer · #15 10-18-2007, 05:17 PM

BUMP.

What would happen if I spliced the return from the distro. to where the cooler line go's?

One of the two lines is building pressure (NOT a line from the pump) and it's enough pressure to keep leaking (at random points....)