1985 BMW 325e E30 Fuel Pump Information

IMAG8199

This picture is from my not-very-happy 1985 BMW 325e E30.

The main fuel pump is 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 as contemporary cars with the M30 engine, i.e., the 5, 6 and 7 series. 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. 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.

 

5 thoughts on “1985 BMW 325e E30 Fuel Pump Information

  1. Hello I have the same car 325e my car had problems starting from time to time but eventually just didint start just cranks but no start . How did you find out it was your external fuel pump that was bad . Also the disk fuel ( you mentioned disk style )filter is the only fuel filter your car has?

    • Hi Alex!

      To be honest, I don’t remember the details any more but I’m happy to try to figure it out again for you.

      If that happened to me today the first thing I’d do would be to disable the fuel pump such as by pulling the relay, and then I’d remove the spark plug wires and attach them to a set of 6 spark plugs taped to a steel pipe that’s attached to the car’s ground. I’d hang that from the open hood and crank the motor and see if there’s a hot spark for each plug. If yes, I’d pull each plug from the head and do a compression check. This stuff is easy and cheap to troubleshoot compared to fuel issues, unless you KNOW you have a fuel issue. And then that might still not be the only issue so you might fix your fuel problem and the car still won’t start, and then you’re puzzled.

      To test the main fuel pump, I undo the hose clamp where the hose from the back of the car connects to the fuel rail, in the back of the latter. If fuel gushes all over my hand, and next time I’ll wear a glove, dammit, then there’s fuel pressure and possibly enough. If there’s none, I worry about the main fuel pump and then I reconnect the hose clamp and run a hot wire (with an alligator clamp) from the battery to the positive of the fuel pump. It should hum, and I should hear fuel sloshing around the fuel rail. If it’s quiet, I suspect the pump or its ground connection. If it works then the pump might be OK but the wiring ain’t, e.g. the fuel relay fried.

      Am I making sense?

      ~Tanya

    • As the fuel filter, I believe so yes. The older models have something that looks like a second filter but that’s actually a sort of fuel pressure shock absorber so that the pulsed pressure from the fuel pump don’t make the injectors squirt erratically. I guess on later years BMW decided the problem wasn’t worth worrying about and they deleted the part.

  2. Thanks for replying, i check my Fuel pump, and its working Properly. there is no power on Fuse 11 but there is power on my fuel pump relay. Any ideas why ? I check pin 13 and there is power also!

    • Hi Alex! Okay, good detective work. So I’m presuming your car has good spark, and good cylinder compression. If these are not validated assumption please go make sure. So, your fuel pump works when you take positive directly to it from the battery, yes? Is there then pressure in the fuel rail?

      ~Tanya

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