How To

How to Clean Injectors of an Inboard Engine?

The state of the injection system directly conditions the operation of a heat engine. An inadequate fuel spraying at the injectors can have several consequences: bad cold start, loss of power, overconsumption of fuel, unstable idle … etc.

Injector fouling is one of the common causes of inadequate fuel spraying. It is caused by the progressive decomposition of the fuel inside the injectors because of the heat emanating from the combustion. This phenomenon is accentuated on outboard marine engines during the winter months. Hence the need to clean the injectors to extend their life and optimize the operation of the engine. 

Fuel injector maintenance on a diesel engine is something that almost any boat owner can accomplish with a few essential tools. The work is particularly easy because you have to take out the injectors and send them to a workshop. Indeed, testing and revising injectors requires specialized equipment and knowledge that most of us do not have.

Here are two tips to help you clean the injectors!

Tip 1: Use an injector cleaning product

The simplest solution for cleaning the injectors of a marine engine is to use a cleaning product. It is a stabilizing additive that mixes with fuel to remove dirt that has accumulated inside the nozzles. This treatment also makes it possible to clean other elements of the injection system, in particular, the injection pump and possibly the fuel lines.

The method of use and dosage of the injector cleaning product varies from manufacturer to manufacturer. In general, the bottle containing the product must be mixed with a certain amount of fuel in the tank, which is defined in the instructions for use. After, you have to sail with the boat until the fuel runs out.

It usually takes several treatments before noting an improvement in the operation of the engine. If you plan to winter your boat or put it inland for more than a month, then it is recommended to double or triple the dosage of the cleaning product recommended by the manufacturer.

This treatment cleans the injectors of the in-board engines and also removes deposits in the combustion chamber and eventually on the valves and the turbo fins. That said, it must be known that cleaning products are ineffective in case of superior fouling.

Tip 2: Use an injector cleaning kit

The injector cleaning kit is a device that cleans the injectors without disassembly. Available in specialty stores and on the Internet, it includes a reservoir for cleaning fluid, a pressure gauge, and a piping system.

Before using a device of this type, it must first be ensured that the engine manufacturer authorizes this operation. To begin, start the engine until it reaches the average operating temperature. Indeed, to successfully clean the injectors, always intervene when the engine is hot. Then connect the hose of the device to the “Schrader” valve located at the injection rail and raise the injection pressure in the system.

Disconnect the electrical cable on the injection pump. Fill the tank of the device with the cleaning liquid in the amount recommended by the manufacturer. Connect the unit to a source of compressed air and adjust its pressure to that of the engine injection system (pressure measured at the ramp).

Start the engine and accelerate several times to route the cleaning fluid to the injectors. The cleaner ensures the role of fuel in this case. Continue the operation until the cleaning liquid reservoir is empty. Usually, the engine should stop at this time.

Wait for 10 to 15 minutes, the time to let the product work inside the injectors. Afterward, disconnect the hose from the cleaning kit. Reconnect the electric cable of the fuel injection pump and accelerate several times. Let the engine idle for a few minutes and then turn it off.

The purpose of this treatment is to route the high-pressure cleaning fluid into the fuel system to remove dirt from the injectors. That said, it is imperative to comply with the device manual and use only products approved by the engine manufacturer. If in doubt, do not hesitate to contact your dealer or a qualified professional.

In the case of very superior fouling of the injectors, it is necessary to carry out an ultrasonic cleaning or test bench. These two operations must be done exclusively at a specialized company.

Cleaning the injectors of an in-board engine: what to remember

There are generally two types of nozzles:   the hole injectors used on the engines to direct injection and nipple injectors for indirect injection engines. These are also abandoned because, in recent years, marine engines are almost all equipped with an electronically controlled direct injection system.

The characteristics of the injectors, namely the shape, the injection pressure, and the direction of the jet, differ according to the injection system and the type of the engine.

In principle, it is recommended to check the setting of the injectors on an inboard engine every 500 hours. To clean the injectors of an inboard engine, you have two possibilities: use an additive or a cleaning kit. In any case, you can optimize the operation of injectors with simple gestures:

  • Always use a good quality fuel.
  • Change the fuel filter regularly.
  • Start your engine from time to time.
  • Regularly add an injector cleaner to the fuel tank. 

Be aware that in case of very superior fouling, it is necessary to carry out a professional treatment at a specialized company.

At the slightest doubt, I advise you to make a call to a professional, this operation is smooth in itself, but in case of error, the consequences can be severe for your engine. To write this article, I approached marine mechanics to ask their advice, but I would take care only of the “prevention” part of the maintenance of the injectors and for a revision of these I would entrust the task to a specialized workshop.

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