Stihl FSA 90 - User Manual

Questions and Answers

K
Kyle LewisDec 1, 2025
Why my Stihl Lawn Mower does not start?
- B
  Brandon McneilDec 1, 2025
  If your Stihl Lawn Mower doesn't start, it could be due to several reasons: * The battery's charge might be too low. Recharge it fully. * The battery could be too warm or too cold. Remove it and allow it to reach a moderate temperature. * There may be a malfunction. Try removing the battery, cleaning the electrical contacts, and reinserting the battery. If 3 LEDs flash red, stop using the lawn mower and contact your Stihl dealer. * The trimmer might be overheating. Remove the battery and let the trimmer cool down. * There could be a fault in the battery itself. Remove and reinsert the battery. If 4 LEDs continue to flash red, discontinue use and contact a Stihl authorized dealer. * Poor electrical contact between the lawn mower and the battery. Remove the battery and clean the...
T
Tamara McneilAug 23, 2025
What to do if my Stihl Trimmer cuts out while using it?
- W
  wandachapmanAug 23, 2025
  If your Stihl Trimmer cuts out during operation, the battery or machine electronics may be overheating. Remove the battery and allow both the battery and machine to cool down. Alternatively, there might be an electrical or electromagnetic malfunction. Try removing and refitting the battery to resolve this issue.
A
Andrew WatersAug 25, 2025
What to do if my Stihl FSA 90 Trimmer cuts out while I'm using it?
- S
  Spencer ThomasAug 26, 2025
  If your Stihl Trimmer cuts out during operation, one potential cause is that the trimmer is too hot; in this case, remove the battery and allow the trimmer to cool down. Another possibility is an electrical fault. To address this, remove the battery and reinsert it, then switch on the brushcutter.
T
tandersonAug 27, 2025
Why does my Stihl FSA 90 cut out during operation?
- J
  jacksonmichaelAug 27, 2025
  Your Stihl Trimmer might cut out during operation because it is too hot or there is an electrical fault. To resolve this, remove the battery and allow the trimmer to cool down. If that doesn't work, remove the battery and reinsert it, then switch on the brushcutter.
M
Michael RobinsonAug 29, 2025
What to do if Stihl Trimmer cuts out during operation?
- J
  Joshua ElliottAug 29, 2025
  If your Stihl Trimmer cuts out during operation, it could be overheating. Remove the battery and allow the trimmer to cool down. Alternatively, there might be an electrical malfunction. Remove the battery, reinsert it, and switch the trimmer on again.
B
Brett LewisSep 23, 2025
Why is 1 LED flashing green on my Stihl FSA 90?
- K
  Kevin TorresSep 23, 2025
  If 1 LED is flashing green on your Stihl Trimmer, it means the state of charge of the battery is too low. Recharge the battery fully.
J
Joseph RamirezSep 17, 2025
How to fix no electrical contact between my Stihl Trimmer and the battery?
- R
  Robin WiseSep 17, 2025
  To fix the issue of no electrical contact between your Stihl Trimmer and the battery, remove the battery, clean the electrical contacts in the battery compartment, and then reinsert the battery.
R
robin13Sep 18, 2025
Why is 1 LED emitting red light on my Stihl Trimmer?
- J
  Jennifer GomezSep 18, 2025
  If 1 LED emits a red light on your Stihl Trimmer, the battery is either too warm or too cold. Remove the battery and allow it to cool down or warm up.
C
Curtis RamirezSep 8, 2025
What to do if the battery jams when inserting it into my Stihl Trimmer?
- E
  emooreSep 9, 2025
  If your Stihl Trimmer's battery jams when being inserted into the power tool or charger, the guides or contacts may be dirty. Carefully clean the guides and contacts to resolve this issue.
T
Terry HartmanSep 6, 2025
What to do if my Stihl Lawn Mower cuts out during operation?
- C
  Christopher RochaSep 6, 2025
  If your Stihl Lawn Mower cuts out during operation, it could be due to the trimmer overheating. Try removing the battery and allowing the trimmer to cool down. It could also be an electrical fault. Remove and reinsert the battery, then switch the lawn mower back on.

Summary

Guide to Using this Manual

Pictograms and Text Symbols

Explains symbols and warnings found in the manual.

Safety Precautions

General Safety Warnings

Essential safety advice for operating the tool.

Intended Use

Describes the correct purpose of the power tool.

Recommended Clothing and Equipment

Details necessary personal protective equipment.

Operating Procedures

Transporting and Cleaning Instructions

Procedures for moving and cleaning the tool.

Accessories and Deflector Symbols

Information on approved parts and deflector markings.

Cutting Attachments

Using Mowing Heads Technique

Technique for using mowing heads.

Using Metal Cutting Attachments Technique

Technique for metal cutting tools.

Pre-Operation Checks

Before Starting Work

Essential checks before operation.

Switching On and During Operation

Starting the tool and safe usage guidelines.

Machine Handling and Maintenance

Handle Types and Storage

Advice on bike/loop handles and proper storage.

Maintenance and Repair Procedures

Procedures for upkeep and fixing issues.

Reactive Forces

Kickout Risk with Metal Attachments

Details kickout risk with metal blades.

Working Techniques

Mowing Head with Nylon Line

Technique for nylon line mowing heads.

Working with Bump Guard

Using the bump guard accessory.

Mowing Techniques

Grass Cutting Blade Use

Information on grass cutting blades.

Approved Component Combinations

Attachment Compatibility Overview

Essential compatibility for attachments and parts.

Mowing & Metal Attachment Types

Lists specific types of mowing and metal cutting attachments.

Handle Assembly

Mounting the Bike Handle

Step-by-step guide for bike handle assembly.

Control Handle Assembly

Mounting the Control Handle

Guide for attaching the control handle.

Loop Handle Assembly

Mounting with Barrier Bar

Instructions for attaching loop handle with barrier bar.

Using the Barrier Bar Accessory

How to use the barrier bar accessory.

Deflector Mounting Procedures

Mounting the Deflector

Instructions for fitting the deflector.

Selecting the Correct Deflector

Importance of selecting the correct deflector.

Cutting Attachment Installation

Power Tool Placement and Fanwheel Mounting

Steps to attach cutting tools and fanwheel.

Attachment Mounting Hardware

Blocking the Shaft for Mounting

Procedure to lock the shaft for mounting.

Fitting Mowing Head

Specific mowing head installation.

Metal Cutting Attachment Installation

Securing the Cutting Attachment

Final steps to secure the cutting tool.

Battery Charging Procedures

Connecting Charger to Power Supply

How to connect the charger.

Charging the Battery

Instructions for charging the battery.

Battery Indicator Lights

LEDs on Battery Explained

Explains battery indicator lights.

Charging Process Indicators

Describes charging status indicators.

Battery Status During Operation

Battery Status During Use

Battery status during use.

Troubleshooting Red LED Error Codes

Troubleshooting battery indicators.

Charger and Harness Information

LED on Charger Explained

Explains charger indicator light.

Fitting the Harness

How to attach the harness.

Shoulder Strap Usage

Instructions for using the shoulder strap.

Harness and Machine Balancing

Full Harness Usage

Instructions for using the full harness.

Balancing the Machine

How to balance the tool for use.

Achieving Floating Position

Achieving the correct working balance.

Starting and Control Operations

Emergency Throwing Off Procedure

Emergency procedure for discarding the tool.

Switching On and Control Overview

Starting the tool and overview of controls.

Using the Set Wheel

How to use the speed setting wheel.

Switching Off Procedure

Stopping the Tool Safely

Instructions for stopping the tool.

Battery and Storage Guidelines

Removing the Battery

Steps to take the battery out.

Storing Machine, Battery, and Charger

Proper procedures for storing all components.

Mowing Head Maintenance

Nylon Line Adjustment and Replacement

How to adjust and replace the nylon line.

Cutting Blades Replacement

Steps to replace cutting blades.

Metal Cutting Attachment Maintenance

Sharpening Metal Cutting Blades

How to sharpen metal blades.

Balancing After Sharpening

Checking balance after sharpening.

Maintenance and Care Schedule

Unit, Controls, and Labels Maintenance

Maintenance for the entire machine and its components.

Battery and Attachment Maintenance

Maintenance for battery and cutting attachments.

Minimizing Wear and Damage

Maintenance Work and Wear-Prone Parts

Advice on maintenance and wear-prone parts.

Main Parts Overview

Key Components Identification

Diagram and list of key components.

Technical Specifications

Battery, Length, and Weight Specs

Specifications for battery, dimensions, and weight.

Noise and Vibration Data

Acoustic and vibration measurements.

Regulatory Information

Transport and REACH Regulations

Regulations for shipping and chemical substances.

Troubleshooting Common Issues

Machine Startup and Operation Problems

Solutions for startup and operational problems.

Troubleshooting Battery and Charger Issues

Battery Life, Charging, and Charger Errors

Solutions for battery life, charging, and charger errors.

Final Procedures and Compliance

Maintenance and Repairs Overview

Procedures for service and repair.

Disposal and EC Declaration

Guidelines for disposal and compliance statement.

Stihl FSA 90 Specifications

General

Type	Brush cutter
Cordless	Yes
Head type	Blade
Handle type	U-type handle
Product color	Black, Orange, White
Vibration emission	3.5 m/s²
Sound pressure level	73 dB
Cutting diameter (max)	380 mm
Power source	Battery
Battery voltage	36 V