Stihl MS 311 User Manual - Page 85

84

MS 311, MS 391

Pressure test

:

Push the ring (1) to the right and

connect the pump (2)

0000 850 1300 to the

nipple (arrow)

– pressurize the fuel tank.

–

Operate the pump until the

pressure gauge indicates a

pressure of 0.5 bar. If this

pressure remains constant for at

least 20 seconds, the fuel tank,

including the tank vent, is airtight.

If the pressure drops, the leak

must be located and the faulty

part replaced.

–

Always install a new fuel hose.

–

Reassemble in the reverse

sequence.

12.10.2 Removing and Installing

:

Take out the screws (arrows) and

pry the AV spring (1) out of the

handlebar.

0001RA408 TG

1

2

4903RA243 TG

1

:

Take out the screw (1).

:

Lower the tank housing (2).

:

Slide the wooden assembly

block (1) between the engine

housing and tank housing.

:

Pry the tank vent (1) out of its

seat using the rib (arrow) for

leverage.

Always install a new tank vent.

4903RA060 TG

1

2

4903RA108 TG

1

1

4903RA244 TG

–

Coat sealing ring of new tank

vent with STIHL press fluid,

b

14

–

Push home the tank vent by hand

until it snaps into position.

–

Reassemble all other parts in the

reverse sequence.

12.11

Fuel Intake

12.11.1

Pickup Body

Any impurities mixed with the fuel

are retained by the pickup body

(filter). The fine pores of the filter

eventually become clogged with

minute particles of dirt. This restricts

the passage of fuel and results in

fuel starvation.

In the event of problems with the

fuel supply system, always check

the fuel tank and the pickup body

first.

– Troubleshooting,

b

3.6 or

b

3.7

Clean the fuel tank if necessary,

–

Open the tank cap and drain the

fuel tank.

–

Pour a small amount of clean

gasoline into the fuel tank. Close

the tank and shake the saw

vigorously.

–

Open the tank again and drain it.

–

Dispose of fuel properly in

accordance with environmental

requirements,

b

1

Section	Page
Contents	2
1. Introduction and Safety Precautions	4
1.1 Introduction	4
1.2 Safety Precautions	5
2. Specifications	6
2.1 Engine	6
2.2 Fuel System	6
2.3 Ignition System	6
2.4 Chain Lubrication	6
2.5 Tightening Torques	7
3. Troubleshooting	9
3.1 Clutch	9
3.2 Chain Drive, Chain Brake, Chain Tensioner	10
3.3 Chain Lubrication	11
3.4 Rewind Starter	12
3.5 Ignition System	13
3.6 Carburetor	14
3.7 Engine	17
4. Clutch	18
4.1 Clutch Drum	20
5. Chain Brake	21
5.1 Checking Operation	21
5.2 Brake Band	21
5.3 Brake Lever	23
5.4 Cam Lever	25
5.5 Pins	26
5.6 Chain Tensioner	26
5.7 Bar Mounting Studs	27
6. Engine	28
6.1 Muffler	28
6.2 Leakage Test	29
6.2.1 Preparations	29
6.2.2 Vacuum Test	30
6.2.3 Pressure Test	30
6.3 Oil Seals	31
6.4 Shroud	32
6.5 Cylinder / Crankshaft	33
6.6 Bearings / Crankshaft	36
6.7 Piston	37
6.8 Piston Rings	39
6.9 Decompression Valve	39
7. Ignition System	40
7.1 Ignition Timing	40
7.2 Preseparator	40
7.3 Ignition Module	40
7.4 Testing the Ignition Module	42
7.5 Spark Plug Boot / Ignition Lead	43
7.6 Flywheel	44
7.7 Short Circuit Wire	45
7.7.1 Testing	45
7.7.2 Removing and Installing	45
7.7.3 Ground Wire	47
7.7.4 Contact Spring	47
7.8 Ignition System Troubleshooting	49
8. Rewind Starter	52
8.1 General	52
8.2 Fan housing	52
8.2.1 Segment	52
8.3 Pawls	52
8.4 Rope Rotor	53
8.5 Starter Rope / Grip	54
8.6 Tensioning the Rewind Spring	55
8.7 Replacing the Rewind Spring	56
9. Servicing the AV System	58
9.1 Buffer on Oil Tank	58
9.2 AV Spring on Oil Tank	58
9.3 AV Spring on Fuel Tank	58
9.4 AV Spring on Front Handle	59
9.5 Stop Buffer at Clutch Side	60
9.6 Annular Buffer at Ignition Side	60
9.7 Handlebar	60
10. Control Levers	62
10.1 Master Control Lever	62
10.2 Throttle Trigger/Interlock Lever	62
10.2.1 Choke Rod	64
10.2.2 Throttle Rod	65
11. Chain Lubrication	66
11.1 Pickup Body	66
11.2 Oil Suction Hose	66
11.3 Oil Pump	67
11.4 Valve	68
12. Fuel System	69
12.1 Air Filter	69
12.2 Baffle	69
12.3 Filter Base	69
12.4 Air Guide Shroud	70
12.5 Carburetor	72
12.5.1 Leakage Test	72
12.6 Servicing the Carburetor	73
12.6.1 Metering Diaphragm	73
12.6.2 Inlet Needle	74
12.6.3 Pump Diaphragm	75
12.6.4 Air Valve	77
12.6.5 Levers on Throttle Shaft	77
12.6.6 Adjusting Screws	78
12.7 Carburetor Adjustment	80
12.7.1 Basic Setting	80
12.7.2 Standard Setting	81
12.8 Carburetor Carrier	82
12.9 Intake Manifold	83
12.10 Tank Vent	84
12.10.1 Testing	84
12.10.2 Removing and Installing	85
12.11 Fuel Intake	85
12.11.1 Pickup Body	85
12.11.2 Fuel Hose	86
12.11.3 Fuel Suction Hose	87
12.11.4 Tank Housing	88
13. Special Servicing Tools	89

Stihl MS 311 User Manual - Page 85

Pressure test, 10.2 Removing and Installing, Fuel Intake, Pickup Body

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