Place the test leads in the 10 amp position,
and the function rotary switch in the DC amp position.
With the ignition switched "off,"
connect the red test lead to battery positive. Do not let the black
lead touch ground.
Connect the black lead to fuel pump test
terminal. The test terminal is located on the end of about a 4"
pigtail on the relay itself. This is typically located in the cowl
area of the vehicle. * Compare readings to chart below. Readings
below are with the vehicle battery at 12.4 volts. A small spark is
normal.
Fuel System
Min-Max Fuel Pressure
Normal Draw
TBI
9 - 13 psig
2 to 4 amps
PFI
36 - 41
4 to 6 amps
CPI
55 - 64
8 to 9 amps
Lower amperage than chart: usually a no start
condition, or long cranking time.
High resistance in fuel pump harness connectors
Fuel pump ground, or fuel pump
Out of fuel in tank
Pump is cavitating from hot fuel
Vehicle battery low.
Higher amperage than chart:
Fuel filter restriction
Fuel return line restriction
If amperage slowly rises after being connected, a
fuel filter should be suspected. Allow pump to run for 30 seconds.
Common sense test: Before condemning any part,
repeat the test above on a vehicle with the same fuel system and compare
your readings.
