Fass II Pump Install
This article is a guide to assist in the install of a Fass II pump
for either the 98.5-02 (VP-44) models or the 03 and up (CP-3)
vintages.The instructions that come with the pump have good detail and
should be used as the main source of information or contact the vendor
that supplied you with the product for technical assistance.
Here is the Fass II pump kit as received from your favorite BOMB
support center, the kit is very complete with most everything you will
need for the task at hand, the only thing additional you will need is
about 15 or 20 zip ties for securing the new fuel line and the wiring
harness. This Fass II kit is of good quality and is put together with
quality materials and longevity in mind.
The first step in this process is to disconnect the existing fuel line
connected to the fuel tank pickup tube; this can be a challenge if you
have never done it before as most of the work is done by feel since you
cannot see the actual tank module, I have found 2 different ways to get
to the feed line pickup, first is to lay under the truck and reach up
and on top of the tank you will feel it or if your truck isn’t equipped
with wheel well liners then you can go in from inside the wheel well,
if you choose this method it will be easier to remove the left rear
wheel and support the truck with a rated jack stand for safety. The
line you are after is the one toward the rear of the truck as you can
see in this picture, notice how the blue retention clip is inside the
plastic fuel line connector. The trick here is to squeeze the two tabs
together as to release the clip from the shoulders of the pickup tube
inlet, squeeze and pull the connector off, the blue retention clip will
stay with the pickup tube inlet , then you simply pull the retention
clip one side at a time towards you till it actually inverts itself, do
this to both halves of the clip and it will slide right off. Don’t
worry about ruining it as it won’t be needed for the Fass install.
OK step two is a good one and you will appreciate it later on. Get a 2
foot piece of old garden hose and slip it over the drain tube from your
fuel filter housing and place a catch bucket under the hose, now open
the filter drain valve, use you air compressor and a blow nozzle at the
line you removed from the pickup tube and with only a few psi blow into
the fuel line to force all fuel from the old line as well as the filter
housing, this step will help you from being soaked in fuel while under
Step three is to remove the fuel line and OEM lift pump going into the fuel filter,
For a 03 and up truck you must actually remove the OEM pump from the
back side of the fuel filter housing. , the old pump is held in
position by 4 Allen bolts, save the bolts as you will need 2 of them
You are now ready to install the pump on the front bed support cross
beam, temporarily mate the pump to the mounting bracket so you can fit
it in place and mark the holes for drilling.
Once you have the holes drilled out to ¼” go ahead and mount the bracket only to the bed support beam.
Now with pump in hand you need to install the fittings to it, I used a
couple rounds of Teflon tape on the fittings before screwing them in,
stay a thread back so you don’t end up with some Teflon tape inside the
fuel system using a 7/8” wrench tighten the two pushlock fittings into
the inlet and outlet of the pump.
Before mounting the Fass II pump to its bracket take a good look at the
markings on the pump, you will find a letter “T” for the fitting that
needs to point toward the tank and a letter “E” to the fitting pointing
towards the engine, using the 4 bolts provided in the kit secure the
Fass pump to the mounting bracket.
Very Important--- Remember the position of the "T" port there is a
small hole in the base directly next to the electric motor, this hole
must aim directly toward the ground! Impropper installation of the pump
can cause premature wear and void manufactures warrenty
Now with the pump installed we need to get the fuel lines going, notice
I taped off the running end of the new fuel line, this is to keep any
dirt out of the system, I mounted the new connector to the other end of
the line, take this end and click it onto the pickup tube nozzle where
you removed the OEM line from. Now stretch out the line and head
towards the inlet side of the Fass pump, cut the line accordingly and
be sure to mount the fuel pre filter between the tank and the pump,
install it in a convenient place for future maintenance of the filter.
Now connect the supplied fuel line to the discharge side of the Fass pump and route the line towards the Mighty Cummins.
If your truck is a 98.5 -02 then mount the fuel line up to the fuel filter housing inlet with the new connector provided.
For a 03 and up truck install the filter block adapter with fuel line
fitting on the back side of the fuel filter housing using two of the
original Allen bolts from the OEM pump. Before mounting up the filter
block adapter use your finger to ensure that the OEM O-ring is still in
place inside the filter housing inlet hole. Use a small dab of oil on
the o-ring to help prevent it from rolling. Using 2 of the original
mounting bolts apply some thread lock provided with the kit and tighten
the adaptor in place. Now secure the fuel line to the filter housing
and we are looking good
OK the pump and fuel lines are complete so let’s move on and get the wiring harness installed
Find the end of the harness that connects to the Fass pump and route it
down thru the engine compartment and head it toward the pump, slide the
connector together at the pump and use some tie wraps to secure the
wiring harness as well as the fuel line from the pump clear up to the
fuel filter housing.
Now up in the engine compartment find the other end of the harness that
clips into the original wiring connection from the ECM to the OEM lift
pump, route it properly and clip it together and secure it with tie
The relay provided with the new harness can be mounted just about
anywhere just keep it away from hot spots, I mounted mine on the
firewall along with the inline fuse
Route the power and ground feed wires around the firewall and connect
them up to the positive and negative battery terminal connections. You
may have some extra wiring here so trim it accordingly to your
application, the wire loom is nice.
OK at this point just go over everything you messed with to insure it is complete and you will be ready for a test fire.
Now remember you still have the catch bucket and hose extension
attached to the filter housing drain? Good......... since the drain
valve is in the open position give the truck a bump start but don’t
start the motor, jump out of the truck and run around to the engine bay
and as soon as fuel comes gushing out the drain tube close the drain
valve, Now turn the key off and then do the key bump one more time to
purge the system of any air in the system, if there is still air in the
lines the new Fass will easily pump it thru and back via the return
line to the tank.
A pic of the pump installed
Start the truck and check for leaks……….have fun dudes the job is
complete, no more worries of fueling issues !!! You will now find that
you won’t watch your fuel pressure gauge like you used to, but when you
do look at your gauge it will look something like this hehehehehe,
feels good huh