John Deere z425 - Manual (Page 26)

Service Engine - 25
SERVICE ENGINE
MX37938
Picture Note: Single cylinder Briggs and Stratton shown.
MX37939
Picture Note: Twin cylinder Briggs and Stratton shown.
MX37910
Picture Note: Twin cylinder Kawasaki shown.
2. Disconnect spark plug wire (A). For the twin cylinder engines, there is
one on each side of engine.
3. Remove each spark plug.
4. Clean spark plug carefully with a wire brush.
5. Inspect spark plug for:
• Cracked porcelain.
• Pitted or damaged electrodes.
• Other wear or damage.
NOTE: In Canada, replace spark plug with resistor plug only.
6. Replace spark plugs as necessary.
M85200
7. Check plug gap (B) with a wire feeler gauge. To change gap, move the
outer electrode. Gap must be 0.75 mm (0.030 in.).
8. Install spark plugs and tighten to 20 N•m (180 lb-in.).
9. Connect spark plug wire(s).
Adjusting Carburetor
NOTE: Carburetor is calibrated by the engine manufacturer and is
not adjustable.
If engine is operated at altitudes above 1006 m (3,300 ft), some
carburetors may require a special high altitude main jet. See your
authorized dealer.
If engine is hard to start or runs rough, check the TROUBLESHOOTING
section of this manual.
Possible engine surging will occur at high throttle with transmission in “N”
neutral and mower engagement lever disengaged. This is a normal
condition due to the emission control system.
After performing the checks in the troubleshooting section and your engine
is still not performing correctly, contact your authorized dealer.
Replacing Fuel Filter
NOTE: Change filter when fuel is low.
1. Park machine safely. (See Parking Safely in the SAFETY section).
2. Let engine cool.
3. Raise operator’s seat.
4. Put a drain pan under fuel filter.
A
A
A
A
A
c
CAUTION: Avoid injury! Fuel vapors are explosive and
flammable:
• Do not smoke while handling fuel.
• Keep fuel away from flames or sparks.
• Shut off engine before servicing.
• Cool engine before servicing.
• Work in a well-ventilated area.
• Clean up spilled fuel immediately.
B