Professional Mail-In Fuel Injector Cleaning Service
Ultrasonic Cleaning & Flow Testing for Automotive & Marine Injectors
Mail-In Service Across the US · Shop Based in Weymouth, MA
Send Your Fuel Injectors to Our Professional Cleaning Lab — Nationwide Mail-In Service
Fuel injectors get dirty. Carbon deposits build up over time, restricting flow and messing with the spray pattern. That's when you start noticing rough idle, poor gas mileage, misfires, and a general lack of power. Fuel additives can help with light buildup, but once deposits have hardened, the only real fix is professional ultrasonic cleaning.
At South Shore Injector, every set of injectors we service goes through a complete ultrasonic cleaning, backflushing, and individual flow testing process. We don't guess. We measure. Each injector is tested before and after cleaning, and you receive a detailed Injector Performance Report showing exactly how your injectors are performing.
We're based in Weymouth, Massachusetts and work with customers across the South Shore, Greater Boston, and the rest of the country through our mail-in service. Just fill out the order form, ship your injectors using the prepaid label we provide, and we'll send them back cleaned, tested, and ready to install. Round-trip USPS shipping is included on every order.
We service gasoline fuel injectors for cars, trucks, boats, motorcycles, ATVs, snowmobiles, and personal watercraft. Whether it's a set of Bosch port injectors from a daily driver or Mercury Optimax injectors from your outboard, we've got the equipment to get them flowing right again.
What We Do
Before & After Data
Every set comes with a detailed Injector Performance Report: flow rates, spray patterns, and leak test results for each injector. You see the numbers before and after cleaning, not just a promise that it worked.
Fast Turnaround
Most orders are cleaned, tested, and shipped back within 1–3 business days of receipt. We keep you updated when your injectors arrive and again when they're on their way back.
Built on Real Experience
South Shore Injector has been cleaning and flow testing fuel injectors since 2014. The shop is run by a marine mechanic with over 10 years of hands-on experience working on inboard and outboard engines.
Every set runs through a GB800 Multi-Port Fuel Injector Tester, the same professional-grade equipment used by OE-level remanufacturers. It was developed by GB Remanufacturing's partner Carbon-Zapp and handles ultrasonic cleaning, volumetric flow testing at multiple RPM setpoints, pressurized leak-down testing, and spray pattern analysis. Every injector gets tested individually, before and after cleaning, so you get real numbers, not guesswork.
All replacement parts (o-rings, pintle caps, micro-filters, and seals) are GB Remanufacturing premium components, the same brand trusted by dealerships and remanufacturers nationwide since 1986.
Automotive, Marine & Powersports
We service gasoline fuel injectors from all major manufacturers for a wide range of applications.
Automotive
MPFI, GDI, and TBI injectors from Ford, Honda, Nissan, Subaru, BMW, and more. OEM brands including Denso, Bosch, Delphi, Siemens, and Keihin.
Marine & Powersports
Mercury Optimax air & fuel injectors, Yamaha GDI, Tohatsu TLDI, plus motorcycles, ATVs, UTVs, snowmobiles, and personal watercraft.
For Repair Shops
Auto and marine shops can send injector work our way on a regular basis — contact us to discuss volume pricing.
Recently Serviced Injectors
Photos and flow data from real cleaning jobs in our shop.
From The Blog
Deep dives on injector cleaning by engine type and common fuel system problems.
What 1,990 Flow Tests Taught Us
Our actual bench data from four years of cleaning — set imbalance, recovery rates, when cleaning fails.
Read →Why Outboards Run Rough
The seven most common causes of a rough-running outboard and how to tell them apart before tearing in.
Read →LS Injector Cleaning Guide
Cleaning LS1, LS3, LQ4 and truck LS injectors — before and after flow data from real swap builds.
Read →Subaru Injector Problems
Why EJ and FA engines suffer from dirty injectors, and when cleaning is a better call than replacement.
Read →Mercury Optimax Cleaning
Air and fuel injectors on Optimax outboards — what to expect, pricing, and how the service works.
Read →Outboard Injector Problems
Yamaha HPDI, Suzuki, Honda, Mercury and Tohatsu outboard injector issues, symptoms, and cleaning.
Read →TBI Injector Cleaning
Throttle body injectors on older GM trucks — why they get dirty and what cleaning actually fixes.
Read →Do Fuel Injector Cleaner Bottles Work?
Honest breakdown of additives vs professional ultrasonic cleaning and when each one is worth it.
Read →Signs Your Injectors Need Cleaning
Rough idle, misfires, poor fuel economy — what injector problems actually look like behind the wheel.
Read →How To Ship Your Injectors
Step-by-step guide to packing and shipping fuel injectors to us safely using the prepaid label.
Read →Common Questions
How does the mail-in process work?
Fill out the order form, ship your injectors to us (we provide a prepaid label), and we'll clean, test, and ship them back with a detailed performance report. Most orders are turned around within 1-3 business days of receipt. Round-trip USPS Ground Advantage shipping is included on every order.
What equipment do you use?
We use a GB800 Multi-Port Fuel Injector Tester, a professional-grade machine developed by GB Remanufacturing and Carbon-Zapp. It handles ultrasonic cleaning, backflushing, volumetric flow testing at multiple RPM setpoints, leak-down testing, and spray pattern analysis. All replacement parts are GB Remanufacturing premium components.
Do you clean marine and powersports injectors?
Yes. We service gasoline injectors for boats (including Mercury Optimax air and fuel injectors, Yamaha GDI, and Tohatsu TLDI), motorcycles, ATVs, UTVs, snowmobiles, and personal watercraft. Same process, same detailed report.
How much does it cost?
$30 per injector for standard MPFI top-feed, $35 for everything else (side feed, GDI, TBI, marine). $15 round-trip USPS shipping with a 4-injector minimum. Optional insurance available. Check our pricing page for full details and examples.
What Our Customers Say
Real reviews from real customers on Google.