Dodge ram truck 3500 1996 Service Manual page 1240

14 - 6 FUEL SYSTEM
BR
DESCRIPTION AND OPERATION (Continued)
in the Fuel Delivery System section of this group for
information. The fuel rail is not repairable.
Fig. 6 Fuel Raii-3.9iJ5.2IJ5.9L Engines—Typical
CAUTION: The left and right sections of the fuel
rail are connected with a flexible connecting hose.
Do not, attempt to separate the rail halves at this
connecting hose. Dye to the design of this connect­
ing hose, it does not use any clamps. Never attempt
to install a clamping device of any kind to the hose.
When removing the fuel rail assembly for any rea­
son, be careful not to bend or kink the connecting
hose.
FUEL RAIL—8.0L ENGINE
The fuel rail supplies the necessary fuel to each
individual fuel injector and is mounted to the lower
half of the two-piece intake manifold (Fig. 5). The
metal, one-piece fuel rail is not repairable.
FUEL TANK FILLER TUBE CAP
The loss of any fuel or vapor out of filler neck is
prevented by the use of a pressure-vacuum fuel tank
filler tube cap. Relief valves inside cap will release
only under significant pressure of 6.58 to 8.44 kPa
(1.95 to 2.5 psi). The vacuum release for all gas caps
is between .97 and 2.0 kPa (.14 and .29 psi). This cap
must be replaced by a similar unit i f replacement is
necessary. This is in order for the system to remain
effective.
CAUTION: Remove fuel tank filler tube cap before
servicing any fuel system component. This is done
to help relieve tank pressure.
QUICK-CONNECT FITTINGS
Different types of quick-connect fittings are used to
attach various fuel system components. These are: a
single-tab type, a two-tab type or a plastic retainer
ring type. Some are equipped with safety latch clips.
Refer to the Removal/Installation section for more
information.
CAUTION: The interior components (o-rings, spac­
ers) of quick-connect fitting are not serviced sepa­
rately, but new pull tabs are available for some
types. Do not attempt to repair damaged fittings or
fuel lines/tubes. If repair is necessary, replace the
complete fuel tube assembly.
DIAGNOSIS A H P T E S T I N G
FUEL P U I P PRESSURE TEST—ALL ENGINES
WITH PRESSURE TEST PORT
NOTE: The fuel pressure test port is used on cer­
tain engines only. On 3.9L/5.2L/5.9L engines, and
when equipped, the test port will be located on the
fuel rail near the throttle position sensor on (Fig. 7).
On 8.0L V-10 engines, this test port is located on
the end of the fuel rail near the engine thermostat
housing (Fig. 5). A sealing cap is screwed onto the
test port
NOTE: The vacuum assisted fuel pressure regula­
tor located at the rear of the fuel rail on 3.9L/5.2L/
5.9L engines is no longer used on any engine.
All fuel systems are equipped with a fuel tank
module mounted, combination fuel filter/fuel pressure
regulator. The fuel pressure regulator is not con­
trolled by engine vacuum.
With engine at idle speed, system fuel pressure
should be 339 kPa ± 34 kPa (49.2 psi ± 5 psi).
WARNING: DO NOT ALLOW FUEL TO SPILL ONTO
THE ENGINE INTAKE OR EXHAUST MANIFOLDS.
P L A C E SHOP T O W E L S UNDER AND AROUND THE
P R E S S U R E PORT TO A B S O R B FUEL.
WARNING: WEAR PROPER E Y E PROTECTION
WHEN TESTING F U E L SYSTEM P R E S S U R E .
(1) Remove the protective cap at the fuel rail test
port (Fig. 5) or (Fig. 7). Connect the 0-414 kPa (0-60
psi) fuel pressure gauge (from gauge set 5069) to the
test port pressure fitting on the fuel rail (Fig. 7).