John Deere stx38 - Manual (Page 48)

3 - 16
4/23/97
DIAGNOSIS ENGINE
ENGINE HARD TO START AND/OR
ENGINE STARTER KICKS OUT
NOTE: Use correct starting procedure as listed in
operator’s manual. The procedure of cranking
the engine for 5 seconds and waiting for 10
seconds will improve starting and decrease
total cranking time. The 10 second pause
allows fuel in the manifold time to evaporate for
improved combustion, reducing the chance of
flooding and muffler backfire.
Test Conditions:
• Control lever in full choke position.
• Crank engine for 5 seconds. If engine does not
start, pause for 10 seconds, then crank for 5 more
seconds. Continue this 5 seconds on, 10 seconds
off cycle until engine starts. If starter kicks out see
step 8. When engine tries to start, continue
cranking beyond the 5 seconds of that cycle until it
starts.
• As engine warms up, move choke control back
gradually. This will help to lessen excessive
exhaust smoke, engine “loading up”, or backfire.
Test/Check Point Normal If Not Normal
1. Cranking speed. At least 300 RPM. If cranking speed is below 300 RPM
check the following:
Low battery output—Load test
battery for correct amperage output.
Engine oil weight too heavy.—Only
multi-viscosity oil is recommended.
Battery or starter terminals
corroded.
Starter failure.
Automatic compression release
(ACR) is not working correctly.
2. Choke adjustment. Choke plate must be completely
closed when throttle lever is in full
choke position. Adjust throttle cable, choke,
governor, and idle speeds.
3. Spark plug.
Use in line spark tester
(D-05351ST)
Clean, undamaged, and gapped
correctly 1.0 mm (0.04 in.). Spark
plug should provide a strong blue
spark. Repair or replace.
4. Carburetor Must have adequate supply of fresh,
clean fuel. Perform fuel flow test.
Connect a remote, gravity feed tank
with fresh fuel after performing fuel
flow test. This procedure will identify
stale fuel problem.
Clean carburetor.
5. Air cleaner. Clean and undamaged. Clean or replace foam pre-cleaner
and air filter element as needed.