2003 Ducati ST4s Fuel Filter Replacement

Remove the
tank from the bike

Now is a
great time to inspect the fuel lines that are attached to the bike.

Place the
tank upside down on a clean towel to protect the tank’s finish.

Remove the
three nuts holding the fuel pump assembly flange to the tank. See Fig 1.

Fig 1 –
View looking front to back of bike.

The fuel
pump flange will need to be loosened from the tank via the three tapped holes
that are on the flange.

Carefully
remove the fuel pump assembly from the tank. The internal hoses are of
sufficient length to allow this to happen. Support the fuel pump assembly upon
the tank as shown in Fig 2. Have a rag ready to protect the tank’s
finish.

Fig 2 –
Fuel pump assembly removed.

Fig 2 shows
the filter and the stock green O-ring. Look over the hoses. If you need,
replace any that need it. Remove the fuel filter and replace it. The O-ring can
be removed over the flange. It will stretch without a problem. Notice that the
area around the flange is liberally greased. Keep the grease and add some.
Ensure that the tank’s flange is liberally greased too. That’s it.

Re assemble
in the reverse order. The O-ring must not be pinched upon re assembly. Note
that there may be a small gap between the two flanges, the value we are talking
is on the order of .020 inches. The O-ring is what seals the assembly not the
two mating flange surfaces.

Options:

Fig 3 shows
a McMaster Carr O-ring on the left and a stock O-ring on the right. The
McMaster Carr is approximately $12 for 5, plus shipping, p/n 9464K548. The
stock is slightly more expensive. The stock Oring seems to be made with some
silicone due to its more elastic properties over the McMaster Carr Oring.

I would
still stretch the O-ring over the flange when using the McMaster Carr O-ring.

Fig 3 – O-ring options

Fig 4 is a
cut a way of a used stock fuel filter Its aluminum, paper, and plastic in
construction. A replacement filter can be bought from the NAPA parts stores. The
NAPA p/n is 3032 for about $4.

Fig 4 – Stock
filter cut a way

Fig 4 is a cut a way of a used stock fuel filter
Its aluminum, paper, and plastic in construction. A replacement filter can be
bought from the NAPA parts stores. The NAPA p/n is 3032 for about $4. The NAPA
filter is slightly longer and smaller in diameter from stock. The barbs on the
ends of the filter are within thousandths of an inch of the stock measurements. Replace the stock filter with the NAPA use the same hose and clamps. The stock plastic filter clamp will not hold the 3032 tightly. Tighten the filter clamp bolt and let the filter float inside of the plastic clamp. The hoses will keep the filter in place. Fig 5 is a view of the filters.

Fig 5 – NAPA 3032 filter & stock.

This is a
guide as to how a fuel filter has been changed on an ST4s, I am not responsible
for results and damages to performing your own work. If you are not adept or
comfortable working on your machine see a dealer..