Section 11 - Fuel System; Fuel System Troubleshooting; Fuel Pump; Fuel System Contamination - Gravely Promaster 100 Service Manual

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
TROUBLE
Hard Starting
Fuel Leak at Carburetor
Engine Floods
Will not idle
Rich idle
idles with Needle Closed
Hunts Erratic Idle
Idles Fast Lean
Will Not Accelerate
Over Rich Acceleration
Hesitates
Will Not Run at High Speed
Low Power
Hunts at High Speed
Runs With Needle Closed
Engine Overspeeds
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

SECTION 11 - FUEL SYSTEM

POSSIBLE CAUSES
(Refer to Key Below)
1, 3, 4, 6, 11, 12, 14, 16, 17, 18
5, 7, 17
5, 15, 17
1, 2, 3, 6
1, 6, 14
14
2, 3, 6, 7, 12, 13, 14, 15, 18
2, 3, 7
1, 6, 11, 12, 14, 15, 16
1, 15
2, 6, 11, 12, 16
1, 11, 12, 14, 16
1, 3, 11, 14, 15, 16, 17, 18
3, 6, 7, 12, 14, 15, 16, 18
14
2, 3, 7, 14
11 - 36
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.
CORRECTIVE ACTION
clean, repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace
repair or replace