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Diagnostic Repair Manual 21

Section 5 Engine Diagnostic Tests

Diagnostic Flow Charts

Use the Flow Charts in conjunction with the numbered tests in this section. Test numbers used in the flow charts

correspond to the numbered tests. The first step in using the flow charts is to identify the correct problem on the

following pages. For best results, perform all tests in the exact sequence shown in the flow charts.

NOTE: For XC6500/XC8000 426cc engine, use flow charts in conjunction with the Generac 426 Service Manual

10000016870.

Problem 9 – Recoil Cord Will Not Pull (208/389/420/459cc Engines)

Problem 10 – Engine Starts Hard and Runs Rough (208/389/420cc Non-EFI Engines)

NOTHING

FOUND

FIX BAD COMPONENT

BAD

VISUALLY INSPECT FOR OBSTRUCTIONS

THAT WOULD CAUSE BINDING OF THE

RECOIL ONCE INSTALLED

AN INTERNAL ENGINE FAILURE HAS OCCURED.

VISUALLY INSPECT EXTERNAL

COMPONENTS FOR A FAILURE

THAT WOULD CAUSE THE

ENGINE TO BE SIEZED

REPLACE

BAD

GOOD GOOD

TEST 33 – TEST

RECOIL

FUNCTION

TEST 34 –

TEST ENGINE

FUNCTION

REPAIR

OR REPLACE

REPAIR

OR REPLACE

BAD

GOOD GOOD

GOOD

TEST 20 –

CHECK

SPARK

CHECK FUEL

SUPPLY

CHECK CHOKE

POSITION AND

OPERATION

TEST 21 –

CHECK

SPARK PLUG

TEST 22 –

CHECK

CARBURETION

TEST 24 –

CHECK VALVE

ADJUSTMENT

CHECK FLYWHEEL KEY

TEST 25 – CHECK

ENGINE / CYLINDER

LEAK DOWN TEST /

COMPRESSION TEST

REPLACE SPARK PLUG

PUSH IN AFTER

STARTING

REPLENISH

FUEL

SUPPLY

REPLACE

IGNITION

MAGNETO

REPAIR OR REPLACE AS NECESSARY

REFER TO ENGINE SERVICE MANUAL

GOOD

ENGINE MISFIRE

APPARENT

LOW FUEL

BAD

ADJUST VALVES

AND RETEST

BAD

TEST 29 – CHECK

AND ADJUST

GOVERNOR

TEST 26 – CHECK

IGNITION MAGNETO

Brand	Generac Power Systems
Model	XT-EFI Series
Category	Portable Generator
Language	English

Generac Power Systems XT-EFI Series User Manual

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Generac Power Systems XT-EFI Series Specifications

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