Can’t find your part?   Contact us:
+1-309-603-4777
Sears Parts Direct
Orders

  • Keep track of the models you own in your profile

    Sign in or Register to view or add models

Schedule a repair
Craftsman
Water Pump

Model # 3902521 Official Craftsman pump

Here are the diagrams and repair parts for Official Craftsman 3902521 pump, as well as links to manuals and error code tables, if available.

There are a couple of ways to find the part or diagram you need:

  • Click a diagram to see the parts shown on that diagram.
  • In the search box below, enter all or part of the part number or the part’s name.

Not all parts are shown on the diagrams—those parts are labeled NI, for “not illustrated”.

We encourage you to save the model to your profile, so it’s easy to access parts and manuals for your appliance whenever you log in.

For DIY troubleshooting advice and repair guides, visit our repair help section.

Owner’s manual

Model diagram and schematic

SEARCH WITHIN THIS MODEL

?

This is the number corresponding to the part on the diagram / schematic

Search
ALL PARTS
Showing 10 of 34 parts  |
Pump Body Gasket J20-18
#15

Pump only diagram

Pump body gasket

Part #J20-18

Replaced by #J20-18C

?
Manufacturer substitution
This part replaces J20-18. Substitute parts can look different from the original.
This item is not returnable
$9.99 | 
9% OFF Phone Price : $10.99
Back Order
Pump Pressure Switch Tube U37-673P
#17

Pump only diagram

Pump pressure switch tube

Part #U37-673P

This item is not returnable
$19.98 | 
9% OFF Phone Price : $21.98
Back Order
Pump Shaft Seal 17351-0009
#2

Pump only diagram

Pump shaft seal

Part #17351-0009

This item is not returnable
$8.89 | 
10% OFF Phone Price : $9.89
Back Order
Pump Shaft Seal U109-6A
#7

Pump only diagram

Pump shaft seal

Part #U109-6A

Replaced by #U109-6B

?
Manufacturer substitution
This part replaces U109-6A. Substitute parts can look different from the original.
$106.69 | 
10% OFF Phone Price : $118.69
Back Order
Switch 2782
#28

Pump only diagram

Switch

Part #2782

Replaced by #TC2153-P2

?
Manufacturer substitution
This part replaces 2782. Substitute parts can look different from the original.
$59.89 | 
9% OFF Phone Price : $65.89
Back Order
Captive Air Tank Inlet Flange (replaces U131-422p) U31-446P
#2

Tank only diagram

Captive air tank inlet flange (replaces u131-422p)

Part #U31-446P

$43.09 | 
12% OFF Phone Price : $49.09
Back Order
Pump Hose Fitting, 90-degree U111-212T
#18

Pump only diagram

Pump hose fitting, 90-degree

Part #U111-212T

This item is not returnable
$27.69 | 
18% OFF Phone Price : $33.69
Back Order
Pump Diffuser J1-39P
#9

Pump only diagram

Pump diffuser

Part #J1-39P

$145.81 | 
8% OFF Phone Price : $157.81
In Stock
Pump Impeller J105-40PE
#8

Pump only diagram

Pump impeller

Part #J105-40PE

$139.59 | 
8% OFF Phone Price : $151.59
In Stock
Pump Check Valve (replaces N12-12p) N166-5P
#20

Pump only diagram

Pump check valve (replaces n12-12p)

Part #N166-5P

$123.89 | 
9% OFF Phone Price : $135.89
In Stock

Symptoms for gas leaf blowers

Choose a symptom to see related leaf blower repairs.

View all

Why does a leaf blower vibrate excessively?

Main causes: damaged fan blade, engine needs a tune up, dirty carburetor…

Read more

What should I do if my leaf blower engine smokes?

Main causes: mixing too much 2-cycle oil with the gas, dirty air filter, clogged carburetor, engine needs tune up…

Read more

What should I do if my leaf blower leaks gas?

Main causes: cracked fuel lines, leaky carburetor seals, damaged fuel tank cap, cracked fuel tank…

Read more

Why does my leaf blower run roughly?

Main causes: stale fuel, dirty air filter, bad spark plug, cracked fuel lines, clogged carburetor…

Read more

Why won't my leaf blower start?

Main causes: bad gas, clogged air filter, cracked fuel lines, clogged fuel filter, dirty carburetor, bad spark plug, wor…

Read more

Repair guides for gas leaf blowers

These step-by-step repair guides will help you safely fix what’s broken on your leaf blower.

View all
How to rebuild a leaf blower carburetor

How to rebuild a leaf blower carburetor

If the leaf blower engine won't start even though there's fuel in the tank, the carburetor could be the problem. Follow …

Read more
Repair difficulty
Time required
 60 minutes or less
How to replace a leaf blower carburetor

How to replace a leaf blower carburetor

The carburetor could be the problem If the leaf blower engine won't start even though there's fuel in the tank. Follow t…

Read more
Repair difficulty
Time required
 15 minutes or less
How to replace leaf blower fuel lines

How to replace leaf blower fuel lines

Leaf blower fuel lines deteriorate with time and eventually can split or crack. You can remove and replace them yourself…

Read more
Repair difficulty
Time required
 60 minutes or less

Articles and videos for gas leaf blowers

Use the advice and tips in these articles to get the most out of your leaf blower.

View all
Top questions about Sears and Sears PartsDirect

Top questions about Sears and Sears PartsDirect

Get answers to frequently asked questions about Sears and Sears PartsDirect.…

Read more
Preparing a leaf blower for long-term storage

Preparing a leaf blower for long-term storage

Follow these easy steps to prepare you leaf blower for long-term storage.…

Read more
Leaf blower common questions

Leaf blower common questions

From what kind of fuel to use to why your leaf blower won't start, here are the questions our experts hear most often ab…

Read more

Parts & More