Chapter 4 Fuel and exhaust systems
2.1 The electrical connector (arrow) for the fuel pump harness is 3.11a The check connector for the fuel pump (located on the
located on the rear side of the fuel tank rear side of the fuse block) (1990 pick-up models)
immediately with soap and water. When you perform any kind of work on
the fuel system, wear safety glasses and have a Class B type fire extin-
guisher on hand.
Carbureted models
1 Before deciding that the fuel pump is defective, it should be tested for
correct pressure while still in the vehicle.
2 To check the fuel pump pressure, you will need a ‘T’ fitting, a length of
hose (with the same inside diameter as the fuel hoses), a fuel pressure
gauge and a tachometer.
3 Loosen the hose clamp and pull the fuel hose off the fuel pump outlet
fitting. Insert one end of the ‘T’fitting into the hose that was disconnected
from the pump and tighten the hose clamp. Cut a short length of hose, slip
one end over the ‘T’ fitting and the other end onto the fuel pump outlet fit-
ting.
4 Connect another length of hose (approximately six inches long) be-
tween the fuel pressure gauge and the remaining end of the ‘T’ fitting. In-
stall hose clamps on all the connections.
5 Loosen the hose clamp
and
disconnect the fuel return hose, which re-
turns fuel to the fuel tank from the carburetor. Slip a short length of hose,
which has been plugged, onto the fitting and install the hose clamp.
6 Connect the tachometer according to the instructions provided by the
manufacturer.
7 Starttheengineandallow itto runforafew momentsbeforetakingthe
pressure reading. This will allow any air in the pump to be vented, which
will ensure an accurate reading.
8 Make sure the engine idle speed is correct, then note the pressure
reading on the gauge and compare it to this Chapter’s Specifications.
9 Stop the engine and observe the gauge. The pressure should remain
constant or return to zero slowly.
10 If the pressure was higher or lower than specified, or if it dropped to
zero instantly when the engine was shut off, the fuel pump is defective and
should be replaced with a new one.
Fuel-injected models
Fuel pump check (2.4L models only)
Refer to illustrations 3.1 la, 3.1 lb, 3. Ilc and 3. lld
11 Turn the ignition switch to Off, open the fuel tank filler cap, apply bat-
tery voltage directly to the check connector for the fuel pump (see illustra-
tions) and listen for the whirring sound of the electric pump through the
filler port. Now squeeze the fuel high-pressure hose-you should be able
to feel pressure in the hose. If you cannot hear whirring, the fuel pump or its
circuit is defective. If you can hear whirring. but pressure does not develop
in the fuel high-pressure hose, the fuel pump is defective.
Fuel pressure check
Refer to illustrations 3.13a, 3.13b, 3.14a, 3.14b, 3.18a,
3.1 Bb, 3.22 and 3.23
12 Relieve the system fuel pressure (see Section 2), detach the cable
from the negative battery terminal and reconnect the electrical connector
for the fuel pump.
13 Disconnectthe fuel high-pressure hose at thedelivery pipe (see illus-
trations). Cover the connection with shop rags to absorb any fuel that
leaks out.
14 Attach your fuel pressure gauge (it must have a range through 50 psi)
to the special adapter (MD998700 or equivalent) as shown (see illustra-
tion). On 3.OL models, attach the special hose (MD998753 or equivalent)
to the adapter as shown (see illustration).
15 Attach the gauge with adapter to the fuel delivery pipe.
16 Reconnect the battery terminal.
3.11 b The check connector for the fuel pump
(located on the right side of the engine
compartment) (1991 and later pick-up models)
3.11~ Fuel pump driving terminal 3.11d The check connector on 1991
(check connector) location on 1989 and and later Montero models is located at
1990 Montero models the right center of the engine firewal
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