Fuel leak at fuel pumps - can I clamp off?
 

the 560SEL has developed a small fuel leak at the rear fuel pumps. Unfortunately I noticed the leak just after I filled up with gas. Might it be possible to clamp off the fuel lines using hose clamps so I can repair the leaks? If so, which fuel lines need to be clamped off? Or do, I have to drain the fuel tank before commencing work?

Also, I understand that normally the copper crush washers are where the leaks are found. Any input is appreciated.

given the age of the car, if you clamp the hoses shut, they will crack and leak.

drain the tank and replace the hose from the tank to the pumps. inspect the rest and replacing them is strongly suggested. also, get all the washers for the connections. unless a pump itself is leaking, this should fix it. i can't see your leak, the light here sucks. good luck, chuck.

I got lucky on my 89 car. The rubber hose from the fuel tank looked recently replaced and I was able to clamp it off with a thin vice grips. That shut off the flow from the fuel tank. (I was just replacing the filter.)

HuskyMan, depending on the leak location you may be able to use a flow stop clamp to shut off gas flow from the gas tank during the repair. It worked for me when I repaired a gas leak on a 1991 MB vehicle. Hose did not crack, as mentioned previously.

If you need to replace any gas hose in the vicinity of the fuel filter/pumps recommend buying the replacement hose from a MB dealer. The hose MB dealers sell is high quality and will last for years.

When I open my fuel cap on the 126 it always goes wooooooooooosh like it is breaking a suction. Seems strange that it doesn't impact performance, but perhaps it is by design and some vent opens at higher differential pressure?

I would think that the suction would give some time to make a simple replacement? I don't recall having any problem when doing the fuel filter but is that after the pump?

The pump might hold back the gas?

If simpler service like a lower hose or a pump or filter required draining the tank I'd have to wonder why they didn't put a shut off valve somewhere. Is there such a beast?

you will see a decent size hose going to the fuel pump to the fuel tank, I usually use vise grips to clamp it. Depending where your leak is, clamping the feed hose may not be needed. theres a check valve in the fuel pump outlet that will prevent fuel from bursting out. you may loose some fuel but you won't loose a full tank.