Gravely 991001-008, Service Manual

Page: 36 / 80

11 - 36
11.1 FUEL SYSTEM TROUBLESHOOTING
The following troubleshooting chart is to be used to
isolate fuel system problems and give possible causes
are corrective action responses
The troubleshooting key is generic and can be used for
several types of transmissions. Use only those
possible causes and corrective actions that apply to the
unit.
11.2 FUEL PUMP
The impulse style fuel pump is the most commonly
used fuel pump. Impulse fuel pumps may either be
mounted externally onto the carburetor fuel inlet or
remotely mounted. These pumps are connected in the
fuel line between the fuel supply and the carburetor or
directly to the fuel inlet.
Impulse fuel pumps are operated by crankcase
impulses created by the up and down movement of the
piston. A hose called a pulse line connects the fuel
pump diaphragm chamber and transmits the impulses
to the pump diaphragm. The impulses actuate the
diaphragm and the flap valves to lift the fuel from the
fuel tank to the carburetor.
11.3 FUEL SYSTEM CONTAMINATION
Any time fuel contamination is found in the fuel system
(dirt, water algae, etc.) replace the fuel, fuel filter and
flush the fuel lines. Remove the carburetor bowl and
clean. Replace all items that cannot be cleaned.
Reassemble the fuel system and check for proper
operation.
SECTION 11 - FUEL SYSTEM
TROUBLE POSSIBLE CAUSES
(Refer to Key Below)
CORRECTIVE ACTION
Hard Starting 1, 3, 4, 6, 11, 12, 14, 16, 17, 18 clean, repair or replace
Fuel Leak at Carburetor 5, 7, 17 repair or replace
Engine Floods 5, 15, 17 repair or replace
Will not idle 1, 2, 3, 6 repair or replace
Rich idle 1, 6, 14 repair or replace
idles with Needle Closed 14 repair or replace
Hunts Erratic Idle 2, 3, 6, 7, 12, 13, 14, 15, 18 repair or replace
Idles Fast Lean 2, 3, 7 repair or replace
Will Not Accelerate 1, 6, 11, 12, 14, 15, 16 repair or replace
Over Rich Acceleration 1, 15 repair or replace
Hesitates 2, 6, 11, 12, 16 repair or replace
Will Not Run at High Speed 1, 11, 12, 14, 16 repair or replace
Low Power 1, 3, 11, 14, 15, 16, 17, 18 repair or replace
Hunts at High Speed 3, 6, 7, 12, 14, 15, 16, 18 repair or replace
Runs With Needle Closed 14 repair or replace
Engine Overspeeds 2, 3, 7, 14 repair or replace
TROUBLESHOOTING KEY
1 Plugged Air Filter
2 Leaky Carburetor Gasket
3 Throttle or Choke Shaft Worn
4 Choke Not Functioning Properly
5 Plugged Atmospheric Vent
6 Air Bleed Restricted
7 Damaged or Leaky "O" Rings
8 Damaged Diaphragm
9 Stuck or Dirty Ball Check
10 Diaphragm Upside Down
11 Plugged Tank or Vent
12 Fuel Pick-up Restricted
13 Idler Port Restricted
14 Damaged Adjustment Needle and Seat
15 Incorrect Float Height
16 Main Nozzle Restricted
17 Dirty, Stuck Needle and Seat
18 Fuel Inlet Plugged