Use and Care Manual

ManualsBrandsJohn Deere ManualsOutdoorsZ235 42 in. 20-HP Hydrostatic Gas Zero-Turn Riding Mower

Service Engine - 31

SERVICE ENGINE

MX51683

2. Disconnect spark plug wire (A) 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 plug(s) 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 if required.

4. Put a drain pan under fuel filter.

MX51682

Picture Note: Standard twin cylinder shown.

5. Slide hose clamps on both sides of fuel filter (A) away from fuel filter

ends using pliers.

6. Disconnect hoses from filter.

7. Connect hoses to new filter making sure the filter arrow is pointing in the

direction of the fuel flow.

8. Install clamps and check for leaks.

Cleaning Engine Screen Guard

The twin cylinder engine incorporates a removable guard over the rotating

flywheel cover at the top of the engine. The guard should be removed to

check for and remove any debris daily in conjunction with checking engine

oil level.

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.

IMPORTANT: Avoid damage! Incorrect installation of fuel filter

may cause engine damage. Install the filter with the arrow

pointing in the direction of fuel flow (towards the engine) for

proper operation.