Service manual

G420F(FE) Service Manual Chapter 6. LPG FUEL DELIVERY SYSTEM 226
Pressure Test
Primary Stage Test Hardware
1. Hand vacuum pump
2. Regulator fuel inlet test fitting 1/4 NPT standard
air coupling)
3. Test gauge fitting (1/4” NPT X 1/4” hose b)
4. Vacuum hose or vinyl tubing
5. 0-60” WC Magnehelic gauge (inches of water
column)
Figure 31. Primary Stage Test Connection
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 31).
2. Connect a compressed air line (shop air ~100 psi)
to the liquid propane fuel inlet of the N-2001
regulator (Figure 31).
Figure 32. Magnehelic Gauge Connection to Hose
Barb
3. Apply compressed air, wait for air to exit the hose
barb in the test port, and then connect the
Magnehelic gauge (Figure 32) to the hose barb
using the vacuum hose or vinyl tubing. This
prevents the gauge from reading maximum
pressure due to the large velocity of compressed
air entering the primary chamber.
4. Make sure there is no leakage at any of the
fittings. The static pressure should read between
40-60” WC on the Magnehelic gauge and
maintain a constant pressure for 60 seconds.
5. If the pressure reading begins to increase, a leak
is most likely present at the primary valve, either
the primary valve o-ring or the valve itself. If a leak
is present the regulator should be replaced.
6. If the pressure begins to decrease, the secondary
seat is probably not making an adequate seal and
is leaking. The regulator should be replaced.
7. If the test is successful, re-install the primary test
port plug and check the fittings for leaks. See
Chapter 5 for installation of the N-2001 regulator.
NOTE : The N-2001 primary stage pressure can
also be tested at idle on a running engine. The N-
2001 primary pressure should be between
40 inH20 (99.635 mbar) and 55 inH20 (136.999
mbar) at 750 rpm, idle.