pressure is set to 255 by the service engineer in Diagnostics;
● An obvious leak of ink from around the pump, the tubing or the manifold.
The following identifies how each of the ink system components can contribute to a loss of
pressure in the system.
Ink Tank Reservoir
● Debris in the ink tank can cause either a partial or a total pressure loss. The debris can
be pieces of foil seals from ink bottles, or other extraneous material that has fallen into the
reservoir.
Pre-pump Filter
● Debris from the ink tank reservoir that has been drawn into the body of the filter can
cause a total, or more usually a partial, pressure loss.
● Over tightening of the connectors onto the threaded stud of the filter body can cause a
partial pressure loss by constricting the olive and reducing the size of the flow aperture; the
actual filter membrane may have become blocked; it has done its job of protecting the
pump.
Pump Assembly
The pump assembly is an electromagnetically-coupled gear pump.
● The pump motor has failed, resulting in loss of drive and hence total pressure loss.
● The pump motor has decoupled from the pump, so that the motor is spinning wildly but
not turning the gears in the pump head, again resulting in a total pressure loss;
● The gears in the pump are worn, resulting in less than totally efficient drive and a
partial pressure loss.
● A leak has developed on the output side of the pump.
NOTE: If the pump motor is turning but the pump itself is not, there will be a normal reading for
Set Pressure, but a zero reading for Read Pressure.
Main Ink Filter
● The filter has fulfilled its task and has eventually collected an excess of debris and
become blocked.
● The PTFE tubing has been incorrectly fitted to the filter. If the tubing is pushed too far
into the elbow assembly, a pressure loss can result due to reduced flow.
● The stainless steel inserts, when pushed into the PTFE tubing, have pared off a little of
the inner wall of the tubing causing a blockage which reduces flow, and hence pressure.
● A leak has developed at an assembled or welded joint.
Ventury Assembly
● The pressure transducer is faulty. Check the transducer and its associated wiring before
suspecting a fault in the pressure circuit hybrid of the IMP PCB.
● The vacuum venture has either become blocked, or the stainless steel insert has been
lost through incorrect assembly.
● A leak has developed at an assembly joint or crack. The manifold has simply become
worn-out after years of ink flow.
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