[click to enlarge]
I was planning on writing a technical article on the fuel pump replacement,
but was unfortunately "forced" into it when the pump in my E36 3-Series died
on us in Las Vegas last year. We spent all night trying to figure out
why the car wasn't starting, checking ignition, electrical components, etc.
Then we decided to check the fuel pump. We pulled out the rear seat,
and pulled off the fuel pump cover. Surprise - the pump was not making
any noise or vibration when we tried starting the car. Disconnecting
the electrical harness and checking the voltage supplied to the pump
revealed a healthy 12 volts - the problem was definitely with the pump.
Luckily for us, one
of Pelican Parts' suppliers had a warehouse a mere two miles away, and we
were able to obtain a new pump the next morning. We then set out to
perform the arduous procedure of a fuel pump replacement in the parking lot
of our hotel! Needless to say these weren't ideal circumstances for
performing this repair, but I thought I would document what we did, as you
may find yourself in a similar predicament if your fuel pump fails on you.
background is in order here. This particular car had been sitting for
an entire year, as I slowly performed a head gasket replacement on it.
I had put about 500 or so miles on it since the head gasket replacement, but
the gas that was sitting in the tank probably still had some old gas mixed
in there. While we were tooling around in Vegas, I let the gas level
get really, really low in the tank. Then I filled up and let the car
sit for about an hour. When we came back to the car to get some
dinner, the car would not start and (as we found out later on) the fuel pump
wasn't working. My conclusion here (and also after looking at the pump
as it came out of the car) was that running the car very low on gas was a
bad thing, as it allows a lot of dirt and debris to be sucked up into the
pump mechanism. So the moral of this story is to make sure that you
don't run your car very low on gas.
Now, let's talk
about fuel tank senders. On the E36 BMW there are two of them (I still
haven't completely figured out why), one on the left side and one on the
right side, which is integrated into the fuel pump. The procedure for
the replacement of the fuel sender on the left side is identical to the
procedure for replacement of the fuel pump on the right side.
Okay, onto the
replacement procedure. The first thing to do is to prep the car.
Remove as much gasoline out of the car as possible. The way I like to
accomplish this is to get some long fuel hose, a small battery operated
carburetor fuel pump, and pump from one car to another. An alternative
approach would be a gasoline hand pump available at most local auto parts
stores. The bottom line is to get as much gasoline out of the tank as
possible. Unfortunately in the parking lot of the hotel, we were not
able to get as much gasoline out as we hoped - under ideal circumstances,
the tank would almost be completely empty.
thing to remember - always disconnect the battery when working near the tank
- you don't want any accidental sparks from any electrical connections.
Some additional warnings too:
- Always have a fire extinguisher handy in
case an emergency arises.
- Gasoline is highly flammable. When
working around fuel and fuel line connections, don't disconnect any wires
or electrical connections that may cause electrical sparks.
- Always remove the gas cap to relieve any
pressure in the tank prior to working on the fuel system.
- Do not use a work lamp when working near
fuel or fuel tanks.
- Gasoline vapors are strong, harmful, and
can cause you to become drowsy and not think straight. Always
perform work in a well-ventilated area with plenty of fresh air blowing
- Always disconnect the batter when
working on the fuel system. Leave it disconnected for at least 30
minutes to allow any residual electrical charge in components to
- Keep plenty of paper towels on hand, and
wear rubber gloves to prevent spilling gasoline on your hands
- Be well grounded - don't do anything
that will create static electricity. Keep all cell phones and pagers
a safe distance away.
The first step is
to remove the back seat from your car. It's simply clipped in place.
Move both the driver and passenger seat all the way forward, crawl in the
back of the car, and simply tug up on the rear seat from the bottom edge.
It should pop up with a minimal amount of force. BMW seems to have
smartly designed the car so that the fuel tank senders and the fuel pump
were very easy to get to - on some cars you need to drop the fuel tank to do
With the back seat
removed, you will see some sound deadening material (Figure
1) with two flaps, one on the right side and one on the left. The
fuel pump is located on the right side of the car - lift up the right side
flap. You will see a circular cover with some wires exiting out of it
(Figure 2). Remove this cover, and the thin
foam seal underneath it (Figure 3). Underneath,
you will see the top of the fuel pump. Disconnect the two connectors
that mate with the pump (Figure 4). Now,
disconnect the fuel lines that feed into the top of the pump. There
will be some gas spillage here - have a roll of absorbent paper towels on
hand. Plug the lines quickly with a bolt or a pen and use a hose clamp
to prevent further leaks.
The pump is held
in place by the big circular disc with the risers on it. There is a
special BMW tool that is used to remove and tighten this black plastic ring.
However, with a large flathead screwdriver and a small hammer, you can
easily tap the plastic ring loose. Carefully remove the ring from the
top of the pump.
Now comes the fun
part. Make sure that you are prepared at this stage, with a heavily
ventilated garage, plenty of paper towels, and rubber gloves (we didn't have
any gloves with us in Vegas). Pull up on the pump, and the entire
assembly should come right out of the tank (Figure 5).
There is a big, thick o-ring that seals the pump to the tank - it will
probably fall to the bottom of the pump, as shown in
Figure 6. Don't let it fall into the tank - you'll then have to
fish it out somehow later on.
Figure 7 shows
this big o-ring from a different angle, having fallen down to the bottom of
the fuel pump screen. Notice in this photo how brown the bottom filter
of the pump looks. For reference, the new pump's screen was completely
Now, you have an
open tank of gas in your backseat (Figure 8).
Needless to say, you don't want to leave the car like this for any length of
time. However, you also don't want to work too quickly, as you don't
want to make any big mistakes.
You could probably
reuse your old sealing o-ring, but I opted for a new one (Figure
9). If you do use the old one, and it doesn't seal well, you will
be plagued with a fuel smell in the interior of your car from that point on.
Figure 10 shows the brand new pump (placed in my
laptop bag, as I didn't have anything else to use as a backdrop in the hotel
parking lot). Notice how white and clean the pump looks compared to
the old one.
Insertion of the
pump into the tank is the reverse of removal (Figure 11).
Make sure that the big o-ring is properly sealed around the outside of the
pump and will seal with the opening of the tank (Figure
12). The new pump sits snuggly on the top of the tank, as is shown
in Figure 13. Spin on the large circular ring
and use the hammer/screwdriver tap procedure to tighten it. I
tightened mine about as tight as I could get it without feeling that I would
break the ring. Reconnect the fuel hoses as is shown in
Figure 14. Use new hose clamps.
Plug in the new
fuel pump, and reconnect the battery after all fumes have subsided.
Then crank the car over and see if it starts. If the car starts and
runs for any length of time then the pump is working fine. Replace the
top cover and foam seal. Then reinstall the back seat simply by
pushing it down into its home position.
Well, there you
have it. Really not that difficult - just a bit unnerving if you don't
have all the info - but we provide that here.
If you would like to see
more technical articles like this one, please continue to support Pelican
Parts with all your parts needs. If you like what you see here, then
please visit our online BMW catalog and
help support the collection and creating of new and informative technical articles like
this one. Your continued support directly
affects the expansion and existence of this site and technical articles
like this one. As always, if you have any questions or comments
about this helpful article, please
drop us a line.