Fluid Circulation Pump
©Aqua-Hot®
250-D03 Diesel Series Service Manual
REV 220302
p. 65
Fuel Pump
The fuel pump draws diesel fuel from the vehicle’s fuel tank
and creates a preset pressure of 145 PSI, which is required
for proper fuel atomization. Reference the illustration below
for a basic overview and understanding of how the fuel pump
functions.
Fuel Pump Cleaning and Maintenance:
1. Check all fuel connections for tightness.
2.
Check the screen filter located in the fuel supply inlet of
the fuel pump for dirt particles. Clean and/or replace if
necessary.
3. To adjust the fuel pressure, refer to Page 73 - Fuel pressure
check and adjustment.
Fuel Pump Testing Procedure:
1. Clamp off and remove the fuel return and fuel supply lines
coming into the Aqua-Hot unit.
2. Attach a short piece of fuel line to both the fuel return and
fuel supply ports.
3. Submerse the opposite end of the temporary fuel supply
line in a container of diesel fuel.
4. Place the opposite end of the temporary fuel return line in
an empty container.
5. Turn the diesel burner ON to activate the diesel burner, and
wait ten seconds.
DO NOT remove the diesel burner at this time� Failure
to do so may result in serious bodily injury.
6.
If fuel does not flow out of the return line into the empty
container, the fuel pump must be replaced,
7.
If fuel does flow through the fuel pump when ran off an
external source, inspect the following in the RV:
• Check the motor home fuel tank for diesel fuel. If the
fuel level is below ¼, the Aqua-Hot diesel burner will
not operate.
• Inspect the supply fuel line for any kinks, which would
prohibit fuel flow.
• Inspect the supply fuel line for cuts, which would cause
the diesel burner to suck air.
•
Inspect the fuel filter to make sure all fittings are tight,
including hose clamps. Make sure the fuel filter is tight.
•
Inspect the Aqua-Hot for loose or cracked fittings.
• Inspect the supply fuel system for loose hose clamps.
• Inspect the fuel pick-up tube in the tank for any loose
connections and/or pin holes in the tube.
Fuel Pump Replacement Procedure:
1. Locate and disconnect the C-plug harness wires that
connect to the flame sensor and the fuel solenoid. Also,
disconnect the ignition cables from the ignition electrodes.
2. Remove the retaining clip that secures the photo disc in
place. Gently lift the photo disc so that it releases from the
NOTE:
Prior to replacing the fuel pump, be sure to inspect
the screen filter in the supply inlet of the fuel pump for dirt
particles. Clean and/or replace if necessary. A plugged
screen filter will restrict fuel from entering the fuel pump.
NOTE:
In order to perform the following procedures, it is
necessary to detach and reattach the diesel burner head.
Be sure to review the detaching/reattaching procedure
starting on Page 47.
Figure 107
Burner Components
1
6
4
3
5
2
FUEL PUMP
OVERVIEW
1. Fuel Nozzle
2. Air Relief Bore
3. Fuel Supply Line
4. Fuel Return Line
5. Fuel Pressure Regulator
6. Fuel Solenoid
