CARBURETOR/FUEL PUMP
90-826883R2 JUNE 1998
Page 3A-15
Fuel System Troubleshooting
General Information
Problems that are thought to be caused by the fuel system may, in reality, be something
completely different. Items, that are shown in the list on the right, could give the impres-
sion that there is a problem in the fuel system
.
1. Propeller
2. Spark Plugs
3. Ignition Timing
4. Ignition Spark Voltage
5. Cylinder Compression
6. Reed Valves
Typical symptoms and solutions in troubleshooting a fuel system are shown below:
Problem: Engine Turns Over but Will Not Start or Starts Hard When Cold
Problem: Engine Idles Rough and Stalls.
Problem: Engine Runs Uneven or Surges.
Problem: Engine Will Not Accelerate.
Possible Cause
Corrective Action
Improper starting procedure used.
Review starting procedure as outlined in “Opera-
tion and Maintenance Manual.”
Fuel tank empty or too low. Improperly mixed fuel.
Contaminants (water,dirt, etc.) in fuel.
Check fuel in tank and replace or add whichever is
necessary.
Fuel tank air vent closed or restricted.
Check air vent on fuel tank. Air vent must be open
all-the-way and free from any contaminants.
Pinched, cut, restricted fuel line or loose fuel line
connection.
Inspect all fuel lines and replace as needed. Tight-
en fuel line connections.
Dirty or restricted fuel filter.
Inspect and replace or clean all fuel filters.
Choke solenoid or enrichment valve not operating.
Inspect solenoid or valve and wiring. Replace as
required.
Needle and seat in carburetor that is either stuck
open (flooding) or closed (no fuel).
Refer to carburetor disassembly in this section.
Improper carburetor jet, restricted jet or idle mix-
ture screw out of adjustment.
Refer to carburetor adjustments in this section.
Improper float level.
Refer to carburetor adjustments in this section.
Low fuel pump pressure.
Disassemble and inspect fuel pump components.
Defective anti-siphon valve.
Inspect valve and/or test engine without valve in
fuel system.