3
9.
FOR GM TBI VEHICLES WITHOUT
A TEST PORT:
Attach the GM TBI test
adapter in place of the fuel line, then con-
nect the fuel line to the adapter. Tighten all
fittings until finger tight, then use wrench to
tighten an additional half turn.
10.
FOR VEHICLES WITH A BANJO BOLT
CONNECTION:
Install banjo bolt test
adapter in place of the banjo bolt. Place
banjo bolt gaskets on either side of the
banjo. Tighten banjo bolt adapter finger
tight, then tighten a half turn with wrench.
11.
FOR VEHICLES WITH A RUBBER HOSE CONNECTION:
Disconnect the fuel line. Leave rubber hose attached to fuel
line. Install matching size adapter and hose clamps on dual
manifold test adapter. Attach test adapter hose to the location
where the fuel line was connected. Connect the fuel line to the
other side of the dual manifold adapter. Use vehicle’s hose
clamps on rubber hose. Tighten securely.
12. Attach hose and pressure gauge assembly to adapter.
TESTING THE FUEL PRESSURE
Make sure approved safety
glasses are being worn during testing. Everyday
eyeglasses only have impact resistant lenses and ARE
NOT safety glasses.
Once the pressure gauge assembly has been installed, you are ready
to test the fuel pressure.
IGNITION ON/ENGINE OFF TEST
1. Turn all accessories
OFF.
(Radio, A/C, headlights, wind-
shield wipers, etc.)
2. Place the end of 6 foot bleed-off hose into an approved,
fuel-safe container. The bleed-off hose must remain in the
container until testing is complete.
3. Re-activate the fuel pump and turn ignition
ON
.
DO NOT
start the engine.
Perform the following checks:
1. Listen for fuel pump starting. Pump should run for about
2 seconds.
2. Check the pressure gauge dial. Fuel pressure should start to
rise. If the pressure does not rise, pressurize fuel system by
turning ignition
ON
and
OFF
several times.
3. Inspect the fuel system for leaks. If any leaks are found, turn
the ignition
OFF
immediately and clean up all spilled fuel!
4. Check fuel pressure reading on gauge. Pressure should rise
to the manufacturer’s specifications and hold steady.
5. If the fuel pressure still does not meet the manufacturer’s
specifications, consult the service manual for corrective
procedures, service the vehicle and retest.
ENGINE ON TEST
1. Start engine and let idle.
2. Read fuel pressure on pressure gauge.
3. If vehicle’s fuel system uses
a fuel pressure regulator
without a vacuum port,
then fuel pressure should
remain constant during
both ignition on-engine off
and idle.
4.
If vehicle’s fuel system
uses a vacuum-actuated
(
c
o
m
-
pensated) fuel pressure regulator, then fuel
pressure should drop approximately 3-10 psi, depending
on manifold vacuum.
5. If the fuel pressure does not meet the manufacturer’s
specifications, consult the service manual for corrective
procedures and service the vehicle.
REMOVING THE TEST GAUGE
1. Turn ignition key
OFF
.
2. Make sure that the bleed-off hose is still in the fuel-safe
container.
3. Fully
DEPRESS
and
HOLD
the pressure relief button until
dial face pointer is resting on stop pin.
4. Disable fuel pump(s).
5. To prevent drips, wrap a shop rag around the fuel rail test port
while disconnecting test port adapters.
6.
FOR CHRYSLER/GM VEHICLES WITH TEST PORT:
Unscrew Chrysler/GM test port adapter and remove from
fuel rail test port.
7.
FOR FORD/LINCOLN/MERCURY VEHICLES WITH
TEST PORT:
Unscrew Chrysler/GM test port adapter from
Ford test port adapter. Unscrew Ford test port adapter from
fuel rail test port.
8.
FOR GM TBI VEHICLES WITHOUT A TEST PORT:
Disconnect gauge hose. Disconnect fuel lines from GM TBI
adapter. Reconnect fuel lines per the instructions found in the
vehicle service manual. Unplug the thermal vacuum port and
replace the air cleaner.
9.
FOR VEHICLES WITH A BANJO BOLT
CONNECTION:
Disconnect gauge hose from banjo bolt
test adapter. Remove banjo bolt test adapter and gas-
kets. Place new gaskets on either side of the banjo bolt.
Re-install, tightening until finger tight, then using a wrench to
tighten up to the specifications in the service manual.
10.
FOR VEHICLES WITH A RUBBER HOSE CONNECTION:
Disconnect gauge hose from dual manifold test adapter.
Disconnect the vehicle’s rubber fuel line by loosening the
hose clamp. Loosen clamp to disconnect the vehicle’s
dual manifold adapter hose. Reconnect vehicle’s rubber fuel
line to original location. Securely tighten hose clamps on
vehicle’s fuel line.
11. Reinstall test cap.
12. Wrap shop rag around the end of the gauge hose to absorb
dripping fuel. Take care not to drip any fuel on hot metal
parts.
13. Remove the bleed-off hose from the fuel-safe container.
Position the gauge hose over the fuel-safe container and
allow any remaining fuel to drain out.
14. Reactivate fuel pump(s) and check for leaks.
15. Repair if needed.
Wipe up all drips or spilled fuel. Place shop rags in an approved
container to prevent fire or serious injury,
Store fuel pressure tester in a safe, well-ventilated area.
GENERAL FUEL PRESSURE DIAGNOSTICS
If the fuel pressure readings do not fall within the vehicle manufac-
turer’s specifications, use the vehicle service manual to diagnose
the problem for that specific vehicle.
High Fuel Pressure Reading
High fuel pressure is usually caused by a problem in the fuel
return line. Check for any restrictions in the flow of fuel back
into the gas tank. Make sure all connections are secure. Check
for cracked or leaking hoses on the fuel pressure regulator.
Low Fuel Pressure Reading
Low fuel pressure readings are usually caused by a problem in
the fuel pressure line. Check for any restrictions in the flow of
fuel from the gas tank. Make sure all connections are secure.
Check for clogged or dirty fuel filter. Replace filter if necessary.
PRESSURE
RELIEF
BUTTON
