Gravity feed issues...


New Member
I'll start off with hello to everyone..........
I have been a been member for a while now, and have been doing all my homework before asking any questions. So now heres my first one,
I have a system set up that has:
A tank outlet to my pump that is 6 inches higher than the pump itself
A belt drive CAT 5CP3120 pump
3/4 feed to pump, only 4 foot from tank to pump, no restrictions
When I hook up a 5/8 garden hose, the pump will prime
When I disconnect the hose and open the valve from the tank to the pump, no water will flow. (Have not yet started the eingine) The pump is like I said, 6 inches below the outlet of the tank, and the water level is at least 8 inches higher than the tank outlet.
Why can I not get any water to flow from the gun to prime the pump? Is this normal? And if this is normal why will it not flow through the pump to the gun to prime?
Water tank outlet 6 inches higher than pump input
Water level is 12 inches+ higher than pump
3/4 unrestricted feed hose to pump with plumbing a total of no more than 4 feet
CAT 5CP3120 belt drive pump
No gravity feed out of the gun it self unless connected to the garden hose
What gives?


Moderator / Sponsor
It sounds like you have a sufficient
feed to the pump. Have you tried running
it off the tank yet?

I believe if you are trying to get water to
flow from the tank through the pump and
through your hp hose and to the gun you
will need a lot more head pressure.

You should have enough of a flooded suction
for the machine to draw from the water tank.


New Member
Yeh Mark,
I was looking for the water to gravity feed out the gun before starting the machine to prime the pump. CAT says to pull the discharge plug and check flow there.
Mark, this unit has a easy start unloader, would that prevent the waster from gravity flowing through the pump to prime it? I would hate to start this unit up to check to see if it pulls water and damage my pump.
BUt if you say it should do the trick, I'll give it a go.

Our Sponsors