Section 4 Engine Diagnostic Tests; Diagnostic Flow Charts - Generac Power Systems GP Series Diagnostic Repair Manual

Engine Diagnostic Tests
Section 4

Diagnostic Flow Charts

There are multiple types of engines on the GP Series generators: 407cc, 389cc, 208cc, 196cc, 163cc, 420cc. Section
3 is divided into difference subsections that provide engine troubleshooting for each type of engine. It is imperative to
identify what type of engine is used in order to effectively troubleshoot the problem.
Problem 9 – Recoil Cord Will Not Pull
TEST 31 – TEST
RECOIL
FUNCTION
BAD
REPLACE
Problem 10 – Engine Starts Hard and Runs Rough
CHECK FUEL
GOOD
SUPPLY
LOW FUEL
REPLENISH
FUEL
SUPPLY
TEST 21 –
CHECK
GOOD
CARBURETION
BAD
REPAIR
OR REPLACE
Diagnostic Repair Manual
TEST 32 –
GOOD TEST ENGINE
FUNCTION
BAD
VISUALLY INSPECT EXTERNAL
COMPONENTS FOR A FAILURE
THAT WOULD CAUSE THE
ENGINE TO BE SIEZED
CHECK CHOKE
GOOD
POSITION AND
OPERATION
PUSH IN AFTER
STARTING
REPLACE
GOOD
MAGNETO
TEST 28 – CHECK
AND ADJUST
GOOD
GOVERNOR
BAD
REPAIR
OR REPLACE
VISUALLY INSPECT FOR OBSTRUCTIONS
GOOD THAT WOULD CAUSE BINDING OF THE
RECOIL ONCE INSTALLED
BAD
NOTHING
AN INTERNAL ENGINE FAILURE HAS OCCURED.
FOUND
TEST 19 –
CHECK
GOOD
SPARK
ENGINE MISFIRE
IS APPARENT
TEST 25 – CHECK
FLYWHEEL
TEST 23 –
CHECK VALVE
ADJUSTMENT
BAD
ADJUST VALVES
AND RETEST
REPAIR OR REPLACE AS NECESSARY
REFER TO ENGINE SERVICE MANUAL
FIX BAD COMPONENT
TEST 20 –
CHECK
SPARK PLUG
BAD
REPLACE SPARK PLUG
BAD REPLACE
TEST 24 – CHECK
ENGINE / CYLINDER
GOOD
LEAK DOWN TEST /
COMPRESSION TEST
GOOD
CHECK FLYWHEEL KEY
GOOD
BAD
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