Equus 3640 - Fuel Injection Pressure Tester - Manual (Page 8)

2
2-1 Fuel
2.1 GENERAL
The tests outlined in this manual are for checking Throttle Body Fuel Injection
(TBI) (see Figure 2) and Multi-port Fuel Injection (MFI) (see Figure 3) fuel
system pressures with the engine running (key on, engine on) and without the
engine running (key on, engine off). Engine running tests are performed with
the engine at idle (unless otherwise noted). The adapter for testing GM vehicles
with test ports is already installed on the end of the gauge hose, while the Ford
adapter is separate. For Chrysler vehicles, depending upon application, either
adapter may be used.
Some fuel injection systems are not equipped with a test port (Schrader valve).
In some cases, these systems may be tested using the tee adapter provided with
the tester:
TBI UNIT
FUEL INJECTORS
THROTTLE BODY
PRESSURE REGULATOR
FUEL CAP
FUEL RETURN LINE
IN-LINE
FUEL FILTER
FUEL PRESSURE LINE
FLEXIBLE HOSE
FUEL TANK IN-TANK
FUEL PUMP
PUMP INLET
FILTER
Figure 2. Typical Throttle Body Fuel Injection (TBI) System
FUEL INJECTORS
PRESSURE
REGULATOR
MANIFOLD VACUUM
HOSE CONNECTION
TEST PORT
(SCHRADER
VALVE)
PULSE
DAMPENER
FLEXIBLE
HOSE
IN-LINE
FUEL FILTER
FUEL RETURN LINE
FUEL PRESSURE LINE
FUEL
CAP
FUEL TANK PUMP INLET
FILTER
IN-TANK
FUEL PUMP
PULSATOR
Figure 3. Typical Multi-Port Fuel Injection (MFI) System