Fuel Pumps (Digifant II)
DIGIFANT II
Fuel Pumps Checking
(One or both pumps do not run with engine running or while cranking)
Requirements
- Fuel pump fuse removed.
- Ignition coil produces spark while cranking starter.
- Disconnect the multi-pin connector from the Digifant E.C.U.
- Bridge terminals 3 and 13 of the connector using jumper wire (with proper terminal ends).
- Switch the ignition ON.
- Both fuel pumps must run.
If both fuel pumps run:
- All the fuel pump wiring circuits are operating properly except the ground circuit from the Digifant E.C.U. to the fuel pump relay.
- Switch the ignition OFF and remove the jumper wire from the Digifant E.C.U.
- Check the continuity of the wire from terminal3of the E.C.U. connector to terminal 85 of the fuel pump relay with an ohmmeter.
Note: Check that the terminal ends of the Digifant E.C.U. connector are not damaged.
If there is no continuity:
- Repair the wiring using wiring diagram.
If there is continuity:
- Replace the Digifant E.C.U.
If only one fuel pump runs:
- Ignition ON, jumper wire installed between terminals 3 and 13.
- Check for battery voltage at the plus (+) side of the inoperative pump with voltmeter.
If voltage is not present:
- Repair the wiring to the fuel pump from terminal 87 of the fuel pump relay.
- Check the continuity of the wire from the negative (-) side of the fuel pump to ground with an ohmmeter.
If there is no continuity:
- Repair the wiring from the fuel pump to ground using the wiring diagram.
If both the power supply and the ground circuits are OK,
- Replace inoperative fuel pump.
If neither fuel pump runs:
- Ignition ON, jumper wire installed between terminals 3 and 13.
- Check for battery voltage to terminals 86 and 30 of the fuel pump relay with a voltmeter.
If there is no voltage present:
- Repair power supply to the fuel pump relay using wiring diagram.
- Check for battery voltage at terminal 87 of the fuel pump relay (with relay installed).
If there is no voltage present:
- Replace the fuel pump relay.
- Check for battery voltage at the positive (+) terminal of each fuel pump.
If there is no voltage present:
- Repair wiring from the fuel pumps to terminal 87 of the fuel pump relay using wiring diagram.
- Switch the ignition OFF.
- Check continuity in the wiring from the negative (-) terminal of each fuel pump to ground.
If there is no continuity:
- Repair wiring for the fuel pump ground circuits using the wiring diagram.
If the continuity is OK,
- Replace the inoperative fuel pumps.
Current Draw - Checking
Requirements
- Battery fully charged.
- Voltage supply OK.
- Remove fuel pump relay.
- Plug US 4480/3 into relay socket.
- Remove fuel pump fuse.
- Connect US 1119 across fuse terminals and set to 10 A scale.
- Switch US 4480/3 ON to run fuel pumps.
- Amperage of combined pumps is approx. 4.2 A
- Plug and unplug individual fuel pump to obtain desired readings.
- Transfer pump: approx. 1.2 A
- Main pump: approx. 3.0 A
A lower reading may indicate a poor ground circuit.
A higher reading may indicate a dragging fuel pump motor that must be replaced.
Delivery Rate - Checking
Transfer pump requirements
- Battery fully charged.
- Voltage supply OK.
- Current draw OK.
- Fuel filler cap removed.
- Remove fuel pump relay.
- Set US 4480/3 to OFF position and install in relay socket.
- Remove black feed hose (1) from fuel sending unit and plug the hose end.
- Install auxiliary hose (2) onto open connection of sending unit and place the other end in a measuring beaker.
- Switch US 4480/3 ON for 10 seconds.
- There should be a minimum of 300 cc of fuel in ten seconds.
Main fuel pump requirements
- Battery fully charged.
- Voltage supply OK.
- Current draw OK.
- Fuel filler cap removed.
- Transfer pump OK.
- Fuel filter OK.
- Disconnect the blue fuel return hose (from the pressure regulator) where it attaches to the main return line near the right shock tower.
- Place the hose end into a measuring beaker.
- Switch US 4480/3 ON for about 30 seconds.
- There should be a minimum of 500 cc fuel in 30 seconds.