PAGE 62 — GENERATOR SERVICE AND TROUBLESHOOTING MANUAL — REV. #0 (08/29/23)
FUEL PUMP RELAY
FUEL PUMP RELAY
The fuel pump relay, sometimes called an run or ignition
relay, provides the DC voltage to the fuel pump. The fuel
pump relay in some generators is mounted onto a base with
terminals to allow connections. Other types of fuel pump
relays used in some generator models do not require a
base and are direct wired.
Testing the fuel relay is simple and does not require any
special tooling with the exception of a multimeter and
proper battery voltage, 12 VDC or 24 VDC depending on
the system being used. The layout of contacts on the fuel
pump relay are shown in Figure 69.
Some fuel pump relays have a suppression diode installed
across the coil to prevent back feed. Other fuel pump
relays used in some generator models may not have this
suppression diode installed. Symptoms for a possible failed
relay are engine cranking with no start.
Testing And Inspection
1. Remove the fuel pump relay from its base holder
(DCA150~DCA600 generators). For DCA6~DCA125
generators, disconnect wiring from relay terminals.
Be sure to mark and tag terminals for reconnections.
2. Using a multimeter, measure the continuity between
the contact pins as referenced in “Fuel Pump Relay
De-Energized Table” (Figure 69A).
3. Next, apply either 12 VDC or 24 VDC to the coil
at pin 8 and apply a ground to pin 7 (DCA150 ~
DCA600) generators. Measure the continuity between
the contact pins as referenced in “Fuel Pump Relay
Energized Table” (Figure 69B).
4. For DCA6 ~ DCA125 generators, apply 12 VDC to
the coil at pin 1 and apply a ground to pin 2. Measure
the continuity between the contact pins as referenced
in “Fuel Pump Relay Energized Table” (Figure 69B).
5. Reinstall the fuel pump relay back into its base holder
(DCA150 ~ DCA600 generators) or reconnect the wires
(DCA6 ~ DCA125) and attempt to start the engine.
6. If the engine does not start, check DC voltage across
the relay coil, and pins 7 and 8 on DCA150 ~ DCA600
generators or pins 1 and 2 on DCA6 ~ DCA125
generators.
7. If the DC voltage is not present at the relay coil along
with a known good ground, refer to associated wiring
diagram to trace relay DC signal path.
Relay Base Holder Testing And Inspection
(DCA150~DCA600 Generators Only)
If the fuel pump relay tested normal, the problem may be
within the relay base holder. DCA6 ~ DCA125 generators
do have a fuel pump relay base holder. The fuel pump
relay base holder is not a ‘sealed type’ and is susceptible
to corrosion and dirt.
This condition can cause the continuity between the relay
pins and the base holder to be compromised. To ensure
good continuity between the relay and its base holder,
cleaning the base holder is required. Perform the procedure
below when cleaning of the relay base holder is required.
Remove the fuel pump relay from its base holder and
spray dielectric cleaner onto the contact pins on the
relay base holder.
With compressed air not to exceed 110 psi (758 kPa),
blow off any dirt and debris that may have accumulated
within the relay base holder contact pins.
Reinstall the fuel pump relay back into its base holder
and attempt to start engine. If engine still does not start,
relay base holder may need to be replaced.
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