Out of vehicle fuel pump test

I need to replace the fuel pump in my brothers 1994 Caravan (3.0 in
tank pump) He can`t afford a new one and I refuse to pay for it
however I have a friend who works at the local junkyard and I can take
any fuel pump from a Caravan there for free (Provided I do all the
labor,etc) ..What would be the best way to see if the pump I took off
one of the junk vans was working before installing it all the way into
my brothers van?..Just leave the wires attached and maybe supplying
voltage to it for a second or two?.. Thanks..... And yes I know
getting a pump from a junked van isn`t the best idea but that`s what
we have to do at this time so hopefully it`ll run for a bit afterwards

 

The pump may be lubricated by the fuel, so I wouldn't run it dry and with no
load.

I'd probably put a pressure gauge on it's output, attach some LONG wires,
and place it outdoors in a small can of gasoline. Don't place the can near
anything important or flammable. Observe all the usual precautions with the
gasoline. If you aren't comfortable that you can do this safely; don't do
it.

If you get any better suggestions, use theirs.

Good luck,
Pat

 

There's another consideration in running it dry besides the lubrication
of the bearings/bushings, though the bearings/bushings lubrication is a
valid one: The commutation (commutator and brushes) also takes place in
the fuel. Three ingredients are needed for a fire/explosion: Air
(oxygen), fuel (gasoline or its vapors), and a spark. In our vehicles,
once fueled at the factory, there is only one ingredient missing between
you and kingdom come: air (oxygen) - and that protection is accomplished
by the commutation (spark generator) being in the liquid fuel (no air).

Even when you run the vehicle out of fuel, the commutation will be
covered in fuel because of several things: (1) The pumping section is
below the commutation section, (2) There is a check valve below the fuel
pump, and (3) When air hits the pumping section, the column of fuel from
the intake sock to the fuel rail remains stationary - so the commutation
remains covered in fuel (no air/oxygen).

If the pump were to get emptied out (a situation not designed for), you
now have the potential for the one missing ingredient for disaster when
you power it up.

 

since you have the pump out might as well bite the bullet and get a new pump so
you don't have to do the job again when the used pump fails

 

Your friend at the yard should be able to point you to a Caravan that
was driven to the yard under it's own power. Failing that, find a Caravan
that is extremely smashed in - the reason why is that it was running up
until
the accident.

Ted