Ryobi
Gas Line Trimmer

Model #990R Ryobi string trimmer

Here are the repair parts and diagrams for your Ryobi 990R string trimmer. 

The diagram(s) below can help you find the right part.  If you’d like help, we invite you to call our customer service number at the top of the page, or click chat.

On this page, you can also find any manuals, installation guides and error code tables associated with this model.

For advice on diagnosing problems with appliances, lawn & garden equipment and other products, check out the videos, repair guides and articles in our DIY section.

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Showing 10 of 155 parts

Line Trimmer Cutting Shield

#11

Lower boom & cutting head Diagram

Line trimmer cutting shield

Part #791-180387
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  180387
This part replaces 180387

$39.83

In Stock

Line Trimmer Blade Nut

#18

Lower boom & cutting head Diagram

Line trimmer blade nut

Part #712-04105
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  147491
This part replaces 147491
This item is not returnable

$7.24

In Stock

Screw

#29

Carburetor and muffler Diagram

Screw

Part #791-181066
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  181066
This part replaces 181066
This item is not returnable

$3.55

In Stock

Line Trimmer Blade Retaining Kit

#NI

All parts Diagram

Line trimmer blade retaining kit

Part #791-180014B
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  180014
This part replaces 180014

$9.36

In Stock

Mounting Muffler

#1

Carburetor and muffler Diagram

Mounting muffler

Part #791-181043
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  181043
This part replaces 181043
This item is not returnable

$3.86

In Stock

Cover

#4

Carburetor and muffler Diagram

Cover

Part #791-181045
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  181045
This part replaces 181045
This item is not returnable

$3.49

In Stock

Wrist Pin

#7

Cylinder and crankcase Diagram

Wrist pin

Part #791-181006
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  181006
This part replaces 181006
This item is not returnable

$4.62

In Stock

Line Trimmer Fuel Line Kit

#22

Clutch,starter module&fuel tank Diagram

Line trimmer fuel line kit

Part #791-181085
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  181085
This part replaces 181085

$14.59

In Stock

Lawn & Garden Equipment Engine Recoil Starter Spring

#9

Clutch,starter module&fuel tank Diagram

Lawn & garden equipment engine recoil starter spring

Part #791-613102
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  613102
This part replaces 613102

$17.07

In Stock

Line Trimmer Retainer Ring

#22

Lower boom & cutting head Diagram

Line trimmer retainer ring

Part #791-612026
?This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including  612026
This part replaces 612026
This item is not returnable

$3.79

In Stock

Symptoms for gas line trimmers

Choose a symptom to see related grass line trimmer repairs.

Main causes: stale fuel, cracked fuel lines, dirty carburetor, bad spark plug, worn piston rings
Main causes: cracked fuel lines, bad carburetor seals, leaky fuel tank cap, damaged fuel tank
Main causes: stale fuel, clogged fuel filter, faulty spark plug, clogged air filter, cracked fuel lines, clogged carburetor

Repair guides for gas line trimmers

These step-by-step repair guides will help you safely fix what’s broken on your grass line trimmer.

October 1, 2013
By Lyle Weischwill
How to replace a line trimmer fuel line

The fuel line on a grass line trimmer deteriorates with time and eventually can split or crack. You can replace it yourself, following these instructions.

Repair difficulty
Time required
 30 minutes or less
October 1, 2013
By Lyle Weischwill
How to rebuild a line trimmer carburetor

If the line trimmer engine won't start even though there's fuel in the tank, the carburetor could be the problem. Follow these instructions to do the job in under 30 minutes.

Repair difficulty
Time required
 30 minutes or less
October 1, 2013
By Lyle Weischwill
How to replace a line trimmer carburetor

If the line trimmer won't start even though there's fuel in the tank, the carburetor could be the problem. Follow these instructions to replace the carburetor in under 30 minutes.

Repair difficulty
Time required
 30 minutes or less

Articles and videos for gas line trimmers

Use the advice and tips in these articles and videos to get the most out of your grass line trimmer.

June 1, 2016

Tips for a hard-to-start grass line trimmer

By Sears PartsDirect staff

These tips may help you get your hard-to-start gas line trimmer running.

June 1, 2015

How to replace a line trimmer fuel line video

By Sears PartsDirect staff

Follow the steps in this video to replace a leaking fuel line in a line trimmer.

March 1, 2015

Easy DIY grass line trimmer repairs

By Sears PartsDirect staff

Learn about some very easy do-it-yourself repairs for a grass line trimmer.