This picture is from a 1985 BMW 325e E30, but it’s very similar to the underside of my 1983 BMW 733i E23 that I looked at just before I looked at the former car.

On both cars, the main fuel pumps are on the driver side, towards the rear.  According to one BMW guru who advised me, and some part numbers I saw, it seems that for practical purposes, these cars use the same fuel pump. In fact, I raided my E30 so as to install its fuel pump on my E24 car, a 1984 BMW 633 CSi. As far as I can tell, these fuel pumps seem to be the same.

Removing this fuel pump from the E30 was tricky. For all the same reasons, I expect the same would be true for the E23. When it comes to fuel hoses, I can either:

• Cut them and then replace them with new hose, or
• Remove them and put them back as they were.

I personally have found old fuel hoses to be the cause of almost all of the fuel leaks I’ve experienced, so I now prefer to cut the old hoses off and replace them with new hoses. I make sure I get high-pressure hoses made for fuel injected systems, since I’ve had some bad experiences where a shop installed less-resilient hose and I ended up with a massive fuel leak while driving on, quite literally, the “Loneliest Road in America,” highway 50 in Nevada.

Another reason why I prefer to cut and replace is that it’s a pain to remove old hoses gently. They tend to have become hardened and tricky to remove.

Regardless, I didn’t like how short the hose is, between the disk-style fuel filter and the main fuel pump, in the picture. Cutting through this hose is difficult because I’m at risk of cutting into the metal of either the filter or the pump, and by then I’ve cut enough hose to cause fuel to leak … and metal on metal tends to make for sparks, and sparks plus fuel can mean a fire, with me maybe ending up dead, or wishing I were.  So, what seemed like a simple task was actually potentially dangerous, in this case.  I personally stopped cutting once I realized the danger, and I weakened the rubber hose and then yanked on it hard enough to essentially tear it apart.

I dimly recall that later vehicles have a different style fuel filter. The later unit is longer, and sits parallel to the fuel pump and even looks somewhat like it, essentially a metal tube of the same approximate girth and length.  The placement is also more inboard. That should simplify things.  So, it’s only on the earlier cars that this sort of placement makes things more difficult.