Fuel Pump to Accumulator Connector Leak

Check the banjo bolt for cracks.

 

Just a side question -- is that some non-Bosch fuel pump with some sort of adapter fitting between the check valve and the fuel pump?

Gasoline is very non-viscous so migrates so easily that I'd still suspect every joint in the area (even the brazed tube into the banjo fitting). The joint between the thin hex of the check valve and that adapter fitting seems to have a copper washer in it but looks a little strange...

 

I just don't like having that extra fitting and joint between the fuel pump and check valve, and think maybe someone might have used the wrong check valve. This picture shows the silver Bosch 1587010536 check valve on the left used on some MB and the goldish Bosch 1587010532 check valve used on the F fuel pumps on the right. They use the same banjo fitting and cap nut, but have different sized threads to screw into the fuel pump:

Image Unavailable, Please Login

Just a thought...

 

No, that would be fine (keeping things parallel). You could also go to a 2mm thick copper washer as the extra thickness gives more deformability to seal up imperfections (and make sure you always use new, soft copper washers -- or you can anneal the old ones in a pinch, but that's sort of a hassle for such an inexpensive washer).

 

Very common. Even the factory had that problem when the cars were new. Due to the design of the fitting at the pump its difficult to counterhold. the pump to tighten them. Often some rotational stress is created and in use it relaxes slightly, enough to cause a leak. I tighten all fittings with both pump and accumulator mounting clamps loose so they rotate freely and tighten them last.

 

100% agree on this, it's super important to do it that way. The pipe connects to the centerline of the fuel pump, but off-center on the accumulator. For a given spacing between the pump and accumulator, here are two "equilibrium" rotational positions the accumulator can be in (+/- up/down angle) to avoid putting stress on the pipe or connections. When I assembled my new fuel pump and accumulator on the mounting sled, I left the mounting clamps loose and gently snugged up the pipe fittings to get the pump and accumulator in whatever relative positions they needed to be in before tightening the fittings all the way. Then tighten up the mounting clamps. There is a small amount of slop where the mounting clamps attach to the sled, which will accommodate the final arrangement of the pump, accumulator, and fuel pipe.