This is what my 97 owners manual states:
"Jet Pump Water Intake
and Impeller Cleaning
Weeds, shells or debris can get
caught on the intake grill, drive shaft(s)
and/or impeller(s). A clogged water intake
may cause troubles such as:
1. Cavitation: Engine speed is high
but jet boat moves slowly due to reduced
jet thrust; jet pump components
may be damaged.
2. Overheating: Since the jet pump
operation controls the flow of water
to cool the engine, a clogged intake
will cause the engine to overheat
and damage engine internal components.
The clogged area can be cleaned as
follows:
In-water cleaning: Pull safety lanyard
to stop engine(s). Let the boat stop by
itself then pull the weedless system
lever. This will lower the water intake
grate. Wait a while to allow weeds or
other debris to fall free from grate.
Thereafter, fully push weedless system
lever and start engine(s). It may
be necessary to repeat the procedure.
In severe conditions if the above
method does not work, the following
can be performed:
– With engine(s) running, put shifter
in reverse position and vary throttle(
s) quickly several times.
– Retry boat.
– If still clogged, restop engine(s) and
rock the boat several times while
repeatedly pressing the starting
button(s) (one at a time) for short
periods without starting the engine(
s).
Most of the time, this will exhaust the
debris from the pump. Start engine(s)
and make sure water flows out from
bleed outlet(s) and jet boat operates
properly.
Out of water cleaning: If the system
is still clogged, shut off the engine(s)
by removing the safety lanyard.
Pull the weedless system lever to lower
the water intake grate. From underneath
boat, manually clean the water
intake area. If the system is still
clogged, refer to an authorized dealer
for servicing.
If the jet pump(s) can not be easily
cleared of debris, the jet boat should
be returned to the trailer or to a boat
lift.
u WARNING
Always remove safety lanyard
from switch to prevent accidental
engine starting before cleaning
the jet pump area.
- CAUTION
Avoid jet boat operation in weeded
areas. If unavoidable, vary jet
boat speed. Weeds tend to entangle
more at steady and slow
speeds. Inspect water intake
grate for damage. Refer to an authorized
dealer for repair as necessary"