Engine Runs But Knocks Or Misses; Engine Will Not Idle; Engine Overheats; Engine Loses Power - Toro 520XI Service Manual

GASOLINE ENGINE
TROUBLESHOOTING (cont'd)

Engine runs but knocks or misses.

Possible Cause
Dirt, water, or stale fuel is in the fuel system
A spark plug lead is loose
A spark plug is faulty
Loose wires or poor connections
Engine overheating

Engine will not idle.

Possible Cause
The fuel tank is restricted
Dirt or water is in the fuel system
A spark plug is faulty
Carburetor idle passages are plugged
The Idle speed adjusting screw is incorrectly set
The fuel pump is faulty
Low compression

Engine overheats.

4
Possible Cause
(3) air intake screens are dirty
Restricted air flow into the engine or radiator
The crankcase oil level is incorrect
The fuel mixture is lean
Excessive loading
Defective thermostat
More coolant is needed

Engine loses power.

Possible Cause
The crankcase oil level is incorrect
The air cleaner element is dirty
Dirt, water, or stale fuel is in the fuel system
The engine is overheated
A spark plug is faulty
Low compression

Engine knocks.

Possible Cause
Old or improper fuel
Internal wear or damage
4 - 4
Corrective Action
Drain and flush the fuel system; add fresh fuel
Reconnect the spark plug lead
Replace the spark plug
Check and tighten wire connections
See ENGINE OVERHEATS
Corrective Action
Check hoses, clean or replace
Drain and flush fuel system; add fresh fuel
Replace the spark plug
Clean or replace carburetor
Reset to factory specifications
Repair or replace
Test compression, correct as needed
Corrective Action
Clean with every use
Inspect & clean the (3) air intake screens & radiator screen
Fill or drain to the full mark
Clean carburetor, check float level, and inspect main jet
Reduce load; use lower ground speed
Replace the thermostat
Check and add coolant
Corrective Action
Fill or drain to the full mark
Clean or replace
Drain and flush fuel system; add fresh fuel
See ENGINE OVERHEATS
Replace the spark plug
Test compression, correct as needed
Corrective Action
Drain system and add fresh fuel
Inspection required
5xi Series Tractor Service Manual