Generac Power Systems GP Series Diagnostic Repair Manual page 52

Section 5 Engine Diagnostic Tests
Figure 5-86. Fuel Gauge and Adapter Tee
Verify all connections are tight, giving a slight tug
8.
on the lines to ensure the connection is secure.
Reconnect the FP harness connector.
9.
Set the key switch to the KSS—Key On position to
10.
activate fuel pump priming.
Check for leaks. If no leaks continue with the test.
11.
NOTE: Cycle between the KSS—Key On and KSS—Key
Off positions a few times to achieve full fuel pressure
reading.
Set the key switch to the KSS—Key Start position
12.
to run the unit. Return the key switch to the KSS—
Key On position when unit starts.
• Observe fuel pressure.
Place a load on the unit while running.
13.
• Observe fuel pressure.
A fully functioning fuel system will have a fuel pressure
range between 40–45 psi.
Results
If fuel pressure is within specifications in the KSS—
1.
Key On position initial fuel system is OK.
If fuel pressure is within specifications with unit
2.
running go back to the flow charts—"Engine Starts
Hard and Runs Rough".
If fuel pressure is within specifications in the KSS—
3.
Key On position but drops below specifications
while running and no external leaks and no faulty
injector(s) replace the fuel pump module assembly.
Fuel pressure too high:
4.
a. Replace the fuel pump module assembly.
Fuel pressure too low:
5.
a. Check for
injector(s).
a. If none replace the fuel pump module
assembly.
46
external leaks and
Test 23 – Check Current Transformer
(CT)
General Theory
An EFI unit monitors load (current) through a current
transformer (CT1) mounted in the control panel. CT1
provides an AC output signal proportional to the current
flowing in the main winding leads (Wire 11 and Wire 44).
Procedure
Electrocution. Lethal voltage may be present
015624
at current transformers (CTs). Do not touch
CTs while primary current is applied. Doing so
will result in death or serious injury.
Set DMM to measure resistance.
1.
See Figure
2.
connector. Probe pins 3D and 3G to measure
resistance. Approximately 378 ohms should be
measured.
a. If proper resistance was not measured, replace
CT1/wire harness
b. If proper resistance was measured, refer back
to the flowchart.
Figure 5-87. ECM Harness Connector
Pin Wire Color
3D Black
3G Black
Test 24 – Testing Fuel Injector (INJ)
Procedure
Disconnect fuel injector.
1.
Measure resistance between each individual
2.
terminal on the injector itself and then from each
connector terminal to ground.
a. If the measurements were consistent with the
values found in Specifications, refer back to
leaking
the flowchart.
b. If the measurements were inconsistent with the
values found in Specifications, replace the
ECU/throttle body assembly
Reconnect the fuel injector connector to the
3.
injector.
DANGER
5-87. Remove ECM
Function
CT (Current Transformer)
CT (Current Transformer)
Diagnostic Repair Manual
(000310)
harness
015043