Service manual

G420F(FE) Service Manual Chapter 6. LPG FUEL DELIVERY SYSTEM 210
N-2007 Regulator Service Testing
For checking the N-2007 regulator/converter
operation, the following tests can be performed (See
Chapter 5 for removal/installation of the N-2007
regulator). To check the secondary regulation
(output) a simple vacuum hand pump can be used
to simulate the vacuum signal transmitted from the
air/fuel mixer when the engine is running. See listing
below for required hardware.
Break-Off Test
Secondary Stage Test Hardware
1. Hand vacuum pump
2. Regulator vapor outlet test fitting 3/4” NPT x 1/4”
hose barb
3. Union Tee 1/4” NPT with three 1/4” NPT x 1/4”
hose barb
4. Vacuum hose
5. 0-3” WC Magnehelic gauge (inches of water
column)
Secondary Stage (Break-Off) Test
1. Connect the vacuum pump, the Magnehelic
gauge and the regulator vapor outlet to the Union
Tee fitting (Figure 34). Make sure there is no
leakage at any of the fittings.
2. Using the vacuum pump slowly apply enough
vacuum to measure above -2” WC on the gauge.
This vacuum signal opens the secondary valve in
the N-2007 regulator/converter.
3. Release the vacuum pump lever and you will see
the gauge needle start falling back toward zero.
When the pressure drops just below the specified
break-off pressure (-0.5 +/- 0.35 “ WC) of the
secondary spring, the needle should stop moving.
4. At this point the secondary valve should close. If
the secondary valve seat or the secondary
diaphragm is leaking the gauge needle will
continue to fall toward zero (proportional to the
leak size). An excessively rich air/fuel mixture can
be caused by a secondary valve seat leak and the
regulator should be replaced.
Figure 34. Secondary Stage Test Connection
Pressure Test
Primary Stage Test Hardware
1. Shop air pressure regulator adjusted to 100 psi
2. Shop air hose fitting (1/4” NPT to air hose)
3. Air hose
4. Test gauge fitting (1/16” NPT x 1/4” hose barb)
5. Vacuum hose or vinyl tubing
6. 0-60” WC Magnehelic gauge (inches of water
column)
Primary Stage Pressure Test
1. Remove the primary test port plug from the side
of the regulator and install the 1/16” NPT hose
barb fitting (Figure 35).
2. Connect a compressed air line (shop air ~100psi)
to the liquid propane fuel inlet of the N-2007
regulator (Figure 35).
Figure 35. Primary Stage Test Connection