What is MPI & EFI and why is diagnostic testing important?

MPI (Multi-Point Injection) and EFI (Electronic Fuel Injection) are systems that deliver fuel efficiently to your engine. Diagnostics help detect issues like misfires, poor fuel economy, or sensor malfunctions before they lead to serious engine problems.

How do you perform MPI & EFI diagnostics?

We use specialized diagnostic tools to read engine sensors, monitor fuel delivery, and analyze engine performance. This allows us to identify problems such as clogged injectors, faulty sensors, or wiring issues accurately.

Can diagnostics prevent engine breakdowns?

They can help. Finding a failing sensor or a fuel delivery problem early lets you fix it before it leaves you stranded or causes bigger damage.

Do you repair issues found during MPI & EFI diagnostics?

Yes. After the diagnosis you get a written estimate, and once you OK it we repair or replace the faulty injectors, sensors or wiring.

How often should MPI & EFI systems be checked?

We recommend a check at the annual or 100-hour service, especially for saltwater boats, and sooner if a warning light comes on or the engine runs rough. Regular checks help catch fuel delivery and sensor problems early.

Can diagnostics improve engine performance?

Diagnostics alone change nothing, but fixing what they find, such as a faulty sensor or a fuel delivery problem, can bring back lost power and fuel economy.

Are MPI and EFI diagnostics safe for my engine?

Yes. Reading fault codes and live data does not change anything on the engine. Which makes and model years we can connect to depends on the engine, so tell us the make, model and year when you book and we will confirm before we come.

Breeze Marine technician viewing live engine data

Breeze Marine technician viewing live engine data (2)

MPI & EFI System Diagnostics

Modern engines rely on a network of sensors to run. If your boat is stalling, surging, or burning excessive fuel, we use a marine diagnostic scan tool to read the fault codes and find the failed component.

Rating:

100% of 100

4 Reviews Add Your Review

$150 /hr

Labor estimate About 1 hour to diagnose, then a quote

Book sends us a ticket; nothing is charged online. Before any work you get a written estimate for labor, parts and the trip fee, and nothing is done without your OK.

Trip fee By distance, one way: $30 in San Pedro, $50 in Long Beach

San Pedro$30
Wilmington, Terminal Island$40
Long Beach: Shoreline, Rainbow Harbor$50
Long Beach Marina, Alamitos Bay$60
Redondo Beach$60
Seal Beach, Huntington Harbour$75
Marina del Rey$85
Newport Beach$110

Farther away: $25 plus $2.50 a mile, one way from our San Pedro shop. No trip fee when the boat comes to our shop, or for plan members. The work of a visit is at least $150; the trip fee is on top.

Registered in California: Breeze Marine Boat Service LLC, San Pedro
Where we work: At your slip from Marina del Rey to Newport Beach, or in our San Pedro shop
Questions first: (213) 693-0224 or submit a ticket

About this service

Computer Diagnostics

Check Engine
Light Diagnosed.

Your boat is run by a complex network of marine sensors. We speak its language. We scan, diagnose, and repair EFI and MPI systems to restore performance.

Scan Tool Tech

We connect a marine diagnostic scan tool to your engine's ECU to read "Check Engine" fault codes and view live data while the engine runs.

Limp Mode Reset

Is your engine stuck at 2000 RPM? The computer has detected a danger (like low oil pressure or overheat) and is protecting itself. We find the root cause and reset the system.

Fuel Injection

Clogged injectors cause poor idle and surging. We test fuel pressure, inspect the regulator, and handle fuel injector cleaning or replacement so the injectors deliver a proper spray pattern.

Digital Forensics.

We analyze the data to find the ghost in the machine.

Connect

We locate the diagnostic port on your harness and plug in our scanner to communicate with the Engine Control Unit (ECU).

Read Data

We don't just read codes. We watch live sensor data (MAP, TPS, IAC) while the engine runs to find values that are out of spec.

Verify

A sensor code doesn't always mean a bad sensor. It could be a wiring short. We use multimeters to verify voltage before replacing parts.

Repair

We replace the faulty component (IAC valve, MAP sensor, etc.), clear the historic codes, and water test to confirm the fix.

Smart Repair.

Fixing the brain of your boat.

Diagnostic laptop reading a fuel-injected marine engine

Replacing the idle air control valve on a marine throttle body

Supported Engines.

We work on these electronic marine platforms.

MerCruiser MPI, ECT, & DTS Systems

Volvo Penta GXi & EVC Systems

Crusader MPI engines (MEFI controls)

Common Questions

Why is my boat surging?

Surging (RPM going up and down) is often a dirty Idle Air Control (IAC) valve or a clogged fuel filter. Marine EFI diagnostics allow us to pinpoint this quickly, and if the valve is worn, an IAC valve replacement fixes it.

Can I clear the codes myself?

Disconnecting the battery might clear the boat check engine light temporarily, but the "History" code remains in the ECU. The problem will return if the underlying sensor fault isn't fixed.

Read the Code.

Stop guessing. Find out exactly what's wrong.

Scan My Engine

Testing Marine Fuel Regulators and Injectors

Poor idle, surging or excessive fuel burn often traces back to the fuel side of an EFI or MPI engine. We test fuel pressure and inspect marine fuel regulators, then clean or replace injectors so they deliver a proper spray pattern. A dirty idle air control (IAC) valve or a clogged fuel filter can cause similar symptoms, so we watch live sensor data before deciding what to replace.

Because a fault code does not always mean a failed part, we verify voltage and wiring with a multimeter before replacing marine fuel system parts or boat sensors. To help us, note when the problem happens (at idle, under load or once the engine is warm) and whether a check engine alarm or limp mode has appeared. After the repair we clear the historic codes and water test the boat to confirm the fix.