Onan NH User Manual

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FUEL PUMPS
These engines are equipped with either a mechanical
fuel pump, pulsating diaphragm fuel pump (pulse
pump), or a remote electric fuel pump. Mechanical
pumps are mounted on top of the engine crankcase,
in front of the carburetor. Pulse pumps are mounted
on the upper right corner of the engine blower hous-
ing on
NHC engines and on the engine rear housing
on
NHCV engines (Figure 17).
' Pulse Pump Test Procedure
Before testing make certain that fuel pump vacuum
line connections are tight and free
of leaks.
1. Operate engine at an idle for five minutes to
ensure that carburetor is full of fuel.
2. Shut engine off and remove fuel inlet line from
fuel pump.
PUMP MOUNTS ON
NHC BLOWER HOUSING
PUMP MOUNTS ON NHCV
ENGINE REAR HOUSING
FIGURE 17. PULSE PUMP LOCATIONS
Mechanical Fuel Pump Test
This type of pump can be tested for proper operation
by checking for fuel flow to the carburetor. Proceed
as follows:
Gasoline is highly flammable and
laWARNlNGl potentially explosive! Use extreme
care when performing this test. Direct fuel flow into a
suitable container and make sure area is well venti-
lated to prevenf accumulation of gasoline fumes.
1. Remove the fuel line from the pump outlet or at
the carburetor inlet.
2. Using some type of container to catch the fuel,
crank the engine over several times. If the engine
is a manual start, operate the pump priming lever
instead. If the pump is electric, simply turn the
ignition switch on to activate the pump.
3. Fuel should spurt out. If it does not, be sure the
problem is not an empty orshutoff fuel tank; then,
remove the pump for repair or replacement.
Spilled fuelcan ignite and cause
k!@@%!l serious personalinjury or death.
Thoroughly clean-up any spilled fuel.
3. Connect avacuum gauge tofuel pump inlet using
a piece of fuel hose with clamps.
4. Start engine and allow to idle for five seconds.
Record vacuum gauge reading.
5. Move throttle control to high idle position. Wait five
;
seconds and record vacuum gauge reading.
6. Shut engine off and remove vacuum gauge hose
from fuel pump inlet. Connect fuel inlet line to
fuel pump.
7. Remove fuel outlet line from fuel pump.
Spilled fuel can ignite and cause
serious personalinjury or death.
Thoroughly clean-up any spilled fuel.
8. Connect a pressure gauge to fuel pump outlet
using a piece of fuel hose with clamps.
9. Start engine and allow to idle forfive seconds. While
holding pressure gauge level with pump outlet
record pressure gauge reading.
10. Move throttle control to high idle position and allow
engine to run for five seconds. While holding
pressure gauge level with pump outlet, record
pressure gauge reading.
.
11. Shut engine off and remove pressure gauge hose
from fuel pump outlet. Connect fuel outlet line
to
fuel pump.
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Onan NH Specifications

General

Brand	Onan
Model	NH
Category	Engine
Language	English