---
product_id: 74474046
title: "Mercury B721 Outboard Shop Manual 3.5-40 H.P., 1972-89 (Includes Electric Motors)"
brand: "haynes"
price: "€ 122.27"
currency: EUR
in_stock: true
reviews_count: 8
url: https://www.desertcart.com.cy/products/74474046-mercury-b721-outboard-shop-manual-3-5-40-h-p
store_origin: CY
region: Cyprus
---

# Fault Finder 700+ visuals DIY techniques Mercury B721 Outboard Shop Manual 3.5-40 H.P., 1972-89 (Includes Electric Motors)

**Brand:** haynes
**Price:** € 122.27
**Availability:** ✅ In Stock

## Summary

> 🚤 Dive into DIY mastery with your Mercury outboard!

## Quick Answers

- **What is this?** Mercury B721 Outboard Shop Manual 3.5-40 H.P., 1972-89 (Includes Electric Motors) by haynes
- **How much does it cost?** € 122.27 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.cy](https://www.desertcart.com.cy/products/74474046-mercury-b721-outboard-shop-manual-3-5-40-h-p)

## Best For

- haynes enthusiasts

## Why This Product

- Trusted haynes brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **DIY Friendly:** Designed for hands-on enthusiasts—no mechanic required!
- • **Visual Learning:** Over 700 detailed pictures and diagrams for easy understanding.
- • **Master Your Outboard:** Unlock the secrets of your Mercury with step-by-step guidance.
- • **Time & Cost Efficient:** Save money and time with expert tips and tricks.
- • **Comprehensive Troubleshooting:** Diagnose issues like a pro with our unique Fault Finder.

## Overview

The Mercury 3.5-40 HP Outboards Service Repair manual from Haynes is your ultimate guide to maintaining and repairing your outboard motor. With over 700 pictures and diagrams, this manual simplifies complex repairs and diagnostics, making it perfect for DIY enthusiasts. Save time and money while gaining the confidence to tackle any issue with your Mercury outboard.

## Description

Mercury B721 Outboard Shop Manual 3.5-40 H.P., 1972-89 (Includes Electric Motors)

## Features

- Every manual is based upon a stripdown & rebuild
- 700+ pictures and diagrams of your vehicle
- Diagnose and solve problems with Haynes’ unique Fault Finder
- We only show DIY friendly techniques
- Save time and money on every job you do

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Manufacturer | Clymer Publications |
| Brand | Haynes |
| Product Dimensions | 20.96 x 1.91 x 27.94 cm; 816.47 g |
| Item model number | B721 |
| Manufacturer part number | B721 |
| Lift type | Electric |
| Item Weight | 816 g |

## Images

![Mercury B721 Outboard Shop Manual 3.5-40 H.P., 1972-89 (Includes Electric Motors) - Image 1](https://m.media-amazon.com/images/I/71hHWsnJhTL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ 5.0 out of 5 stars







  
  
    Just the job
  

*by M***. on Reviewed in the United Kingdom on 21 April 2024*

The book answers all of the questions that I had and will enable me to service my 40 year old Outboard more easily.The next day delivery was, as usual, awesome.

### ⭐⭐ 2.0 out of 5 stars







  
  
    Handy book... if you're an Outboard Mechanic..
  

*by S***N on Reviewed in the United Kingdom on 22 August 2022*

Well... the book was useful I guess, although you can get the same diagrams free online. I have a 1984 Mercury 3.5hp and didn't find the book as comprehensive as I would have liked.

### ⭐⭐ 2.0 out of 5 stars







  
  
    Not the first manual for me
  

*by M***N on Reviewed in the United Kingdom on 12 January 2014*

I have a lot of experiences from manuals, Clymer, Haynes and others, for cars, motorcykles, outboards and inboards. This one is bad in some cases and fair in some. I still don't know how to exchange impeller on my 9,8 Hp 2 stroke Merc from 1972. I will therefore buy a book from Seloc and see if that one is better. If not, I'll use more force to take apart.My impeller looks different to them in the book.On my Honda Goldwing I used both Clymer and Haynes, and that was better than using one of them.

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**Shop now:** [https://www.desertcart.com.cy/products/74474046-mercury-b721-outboard-shop-manual-3-5-40-h-p](https://www.desertcart.com.cy/products/74474046-mercury-b721-outboard-shop-manual-3-5-40-h-p)

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*Product available on Desertcart Cyprus*
*Store origin: CY*
*Last updated: 2026-03-20*