Appendix 1 - Troubleshooting
Symptom
Possible Cause
Resolution
HP hose vibration, and/or
Excessive pressure fluctuation,
and/or
System unable to come up to
55 bar (800 psi)
HP pump is starved of water
and is cavitating
A black high pressure hose vibration or the system inexplicably failing to come up to pressure is usually
a simple issue to resolve. 95% of the time the issue is due to a blockage or flow restriction upstream
from the high pressure pump, causing it to cavitate. Several possible causes exist and there are a
number of things to explore. You are looking for items that can restrict flow to the high pressure pump,
so you are searching upstream from there. Check the following:
1.
Replace the pre-filter if dirty. A dirty filter can block flow, starving the high pressure pump of water
supply. Do not just clean it as sometimes it can look clean but is still clogged.
2.
Ensure the pressure supply unit is within 2 metres (6 feet) of sea level. The system being too high
can make the lift pump work too hard and decrease its effectiveness. This can starve the high
pressure pump of water supply.
3.
If you recently changed the pre-filter, did you leave any small parts of the plastic wrapping on it,
which may now be clogging the flow in the filter housing?
4.
Ensure the pre-filter cartridge is only a particle filter, not a combination carbon and particle filter.
Some carbon or dual carbon/particle cartridges are labelled with micron ratings and look like
particle filters. These can restrict flow and cause cavitation.
5.
The seawater end of the intake hose has a check valve. If something gets in there, it can jam and
restrict flow. It is easy to disassemble and check, but be careful of small parts. Turn both sides of
check valve counter clockwise against each other and it will separate in the middle. Inspect for
items that are small enough to get through the strainer and clog the valve.
6.
Is the intake hose damaged and sucking air in? This could be from continual rubbing against a part
of the boat that wore a small hole in the hose. If so, this hose needs repair or replacement.
7.
If you have installed your Rainman system, check all items upstream from the pressure supply unit
to see if something is starving the Rainman of free flowing water. We recommend all fittings on
the intake side should be a 3/4’ inner diameter. The Rainman system should have exclusive use o
f
the through hull while in operation.
8.
Inspect the impeller on the lift pump for wear. Replace if necessary.