Need help with identifying fuel hoses.

#1

RealOEM seems to have contradictory info re. my 4/87. I was thinking about testing the anti-sputter device, but I’m not dead sure what the hoses do that I can see when I remove the access panel behind the passenger seat. These are the two hoses that exit from the fuel level sending unit.

This diagram indicates that one hose goes to the external pump and the other is the fuel return from the engine. If this is correct, then I’m in business.
http://www.realoem.com/bmw/showparts.do?model=1113&mospid=47309&btnr=16_0173&hg=16&fg=15

But this diagram indicates that both hoses are both part of the ventalation system.
http://www.realoem.com/bmw/showparts.do?model=1113&mospid=47309&btnr=16_0107&hg=16&fg=1

#2

What exactly are you trying to test? I’ve never heard any mention of an “anti-sputter device”.

#3

Carr Industries makes a widget they call a fuel accumulator. It works by creating a small surge volume of fuel between the low P and high P pumps. The fuel comes from the return line.

http://store.nexternal.com/shared/StoreFront/default.asp?CS=carronline&StoreType=BtoC&Count1=732921779&Count2=650062203&CategoryID=28&Target=products.asp

Reports on the success of the overpriced piece of plastic are mixed. A little imagination, a couple T connectors and a big fuel filter would accomplish the same thing.

#4

Scott - it looks like the larger pipe is the outlet, smaller one the return.
Ed

#5

It has been over a year since I had the tank out and things are a bit fuzzy. But I do know that the expansion tank line does run to that area. That implies that the fuel return from the engine bay goes to the fitting on the top of the tank closer to the driver’s side.

The reason that I know that the expansion tank line goes there as I managed to trap it on the side of the tank the last time I re-installed the tank (after acid cleaning and sealing). I had to pull that line back into the wheel well and then fish it back to the top of the tank…

#6

Guys, this was my initial impression too, but the diagram that shows the vent lines has me stopped. Notice in the picture above one of the pipes curves as it exits. Then look at the RealOEM diagrams. One shows angular pipes and the other shows a curved pipe. The curved pipe is in the diagram that calls them vents. And of course I have the curved pipe.

And what’s with the big vent tank in the vent diagram. I know of no big vent tank near the right rear wheelwell. Does that really exist? And so damn many hoses. Who would come up with that cludge/

#7

The tank is there. The plate that covers it is probably buried under a half inch of undercoat and road trash.

#8

I have a 89, build date is 6/88. Ive had the fuel tank out and every hose replaced. The small tank is a plastic return tank. Fuel does recirculate from the fuel tank to that plastic tank. Its located behind the fuel filler neck. If I recall correctly, one connection is from the fuel filler neck to the plastic tank, I guess for overflow. A plastic cover hides it all. I had to replace every rubber/plastic fuel hose. I have never experienced any fuel starvation problems since the hoses have been replaced.