1988 420 fuel leak - PeachParts Mercedes-Benz Forum

884201972 · #1 10-21-2007, 11:41 AM

Just purchased '88 420sel that has had minimal use for last 2 years. Only with car running, it leaks fuel from fuel pump area. Appears to be coming from top of fuel filter area and dripping on ground. Does this sound like the fuel delivery hose from tank? With car off, no more leak. Also note that it does not appear to leak with low fuel in tank. Am baffled at this point. Thanks, Steve

slk230red · #2 10-21-2007, 11:59 AM

Quote:

Originally Posted by 884201972

Just purchased '88 420sel that has had minimal use for last 2 years. Only with car running, it leaks fuel from fuel pump area. Appears to be coming from top of fuel filter area and dripping on ground. Does this sound like the fuel delivery hose from tank? With car off, no more leak. Also note that it does not appear to leak with low fuel in tank. Am baffled at this point. Thanks, Steve

If it's only when car is running and coming from the fuel filter area, then I would guess that it is probably a copper washer leaking at one end of the fuel filter. I would try tightening the fittings to see if that stops the leak.

If it was the fuel delivery hose, then I would think that it would also leak when the engine is not running.

cudaspaz · #3 10-22-2007, 10:06 AM

I would take it to a reputable M/B shop and have it put up in the air.

You probably have brittle fuel hoses as well as a banjo fitting copper crush washer leaking.

If you replace a crush washer, chances are you will create another leak from pinching off/disturbing the rubber fuel hoses.

If it were my vehicle, I would have (all) the rubber hoses replaced and have the fuel filter/pump package resealed with new washers.

This is definitely not a job you want to try to tackle in your driveway as it is extremely messy with the fuel that goes everywhere, not to mention extremely dangerous to do on the ground especially with those older cars and their notoriously brittle rubber fuel hoses.

If you snap a main fuel supply hose, you can be in big trouble, real quick.

884201972 · #4 11-13-2007, 10:56 PM

Found the leak! Turned out to be the fuel delivery hose from tank to filter. No more leak. On to next issue. Car always starts almost instantly-hot or cold. New spark plugs as old ones were carboned up from sitting and idling for two plus years. Idles fine, drives fine, but will stall out sometimes when slowing down, like going around a corner. Push it into neutral, car restarts instantly and away you go. Might do it again before I get home, and then again it might not. Fuel pump relay failing? Advice please.