Fuel Injection Problems? 10 Most-Common Issues & Fixes

Fuel injection systems have been around for decades in various forms. The current generation involves high-pressure fuel pumps, separate injectors for each cylinder in the engine, and multiple fuel lines to transport the fuel to and from the fuel tank.

No matter the style of fuel injection, the same 10 most common problems can plague each system, but we have the simple answers to fix them.

#1 – Your Fuel Injectors Are Clogged

Your fuel injectors have tiny orifices in them to atomize the liquid fuel and make it spray a fine mist. It doesn’t take much to clog an injector.

There is a pre-filter on the fuel pump, and a secondary filter for the fuel line, and still dirt can get to the injectors and build up a blockage.

Blockage can also occur from fuel contamination, fuel breakdown due to improper storage, and heat soak. One clogged injector can cause multiple problems from stumbling, excessive vibration in the engine, and poor gas mileage.

Car mechanic fixing fuel injector at two camshaft gasoline engine

How to Fix It

Most clogged injectors can be cleaned with a simple pour-in additive to your fuel tank. Severely clogged injectors may need to be removed and sent to an injector specialist to be thoroughly cleaned if the additive won’t fix the problem.

The worst case is that one or more injectors need to be replaced. If one is to be replaced, they all should be replaced together as a balanced set.

#2 – Your Fuel Injectors Are Damaged

Your fuel injectors are sensitive to overheating under severe use which can cause internal or external leaks, seal damage, and nozzle damage.

Most injectors are properly sized for flow rate and type from the manufacturer, but often car enthusiasts add extra components that stress the injectors to a failure.

How to Fix It

A damaged seal on a fuel injector can often be replaced economically.

It is a large job to remove a portion of the parts on the engine to remove a fuel injector, and it may be a job for a professional mechanic.

If the injector itself has damage, it should be replaced. If you’re replacing one, you should replace all to ensure a balanced set is being used.

#3 – Your Fuel Pump Is Failing

Your fuel pump is a main part of your fuel injection system, and without it, the fuel doesn’t flow from the fuel tank to the engine. Oftentimes the fuel pump doesn’t stop working without another cause like a blown fuse or a relay going bad.

Fuel pumps have a distinct whining sound when working properly. And that tone can change indicating the fuel pump is starting to fail.

More signs of a failing fuel pump are a loss of acceleration from the vehicle, a misfire in the engine, or a stumbling idle because of limited fuel making it to the engine.

If you need help with fuel pump problems, check out this article.

How to Fix It

A failing fuel pump often will give warning signs that it needs to be replaced. They can be rebuilt by a specialist, but often it’s more economical to replace the fuel pump with a new one.

You may need to remove the fuel tank from the vehicle unless there is a panel in the floor of your vehicle providing easier access for pump replacement.

Just remember that fuel is very flammable, and you should wear proper protective apparel when handling fuel-related components.

#4 – Your Fuel Filter Is Clogged

Your fuel filter screens small contaminants out of the fuel before they can reach your fuel injectors. The filter has a small capacity and it is recommended to be changed frequently of 30,000 – 40,000 miles.

If you don’t change it, the chances are that it will fill with contaminants and start to clog the flow of fuel. This leads to a lean condition of minimal fuel reaching the engine.

How to Fix It

The fuel filter is one of your basic maintenance items that should be changed at a frequency based on mileage or time. You need basic hand tools to change the filter, or it can be done by your favorite mechanic.

#5 – Installation Errors Are Causing Extra Problems

Most of the parts in the fuel injection system are easy to install, but sometimes parts are tricky or need a little extra force to snap together.

A simple installation error can cause a misfire, a leak, and a check engine light to appear.

How to Fix It

In the case of installation errors, the remedy is just to take a moment to install the parts correctly assuming there isn’t a manufacturer defect causing the issue.

#6 – Your Engine Control Unit (ECU) Has A Problem

Your Engine Control Unit uses signals from the engine sensors to control how the engine runs, when the spark plugs fire to ignite the fuel, and to turn the fuel injection parts on and off at the correct time.

If the ECU goes bad due to an internal issue or a power surge, it may stop working or start controlling engine functions at the wrong time.

How to Fix It

The ECU has an internal circuit board that may have an issue because of a bad diode, corrosion on one or more connections, or a capacitor that has gone bad. There are specialist companies that can fix broken components and test the ECU before returning it to you.

The second option is to replace the ECU with a comparable unit. If you can find one from the same vehicle, it may be as simple as removing your original and replacing it with a new or quality-used ECU.

Be careful to mix model years or between vehicles because wiring harnesses change year to year and they may not be exactly the same.

#7 – You Have An Engine Misfire

Engine misfires can be caused by several different issues, but a common problem is due to an incorrect air-fuel ratio.

The optimum ratio of air to fuel will ensure the optimal burning of each component. If one component increases or decreases, the non-balanced ratio can cause an engine misfire.

How to Fix it

Fixing a misfire can be a tricky subject because there are many components in the fuel injection system that can cause a misfire.

To start, use a diagnostic tool to scan the trouble codes to understand what the car is sensing. It could be a bad engine sensor, a low fuel pressure condition, or a bad injector.

Many times it is a simple fix by changing one of the components like a fuel filter.

If you don’t have a diagnostic tool or don’t feel comfortable troubleshooting the issue, take it to a professional mechanic who can determine the cause and fix the issue.

#8 – Your Fuel Economy Negatively Changes

After you own your car for a few months, you should get an understanding of how well it does with fuel mileage. You can expect your car to stay consistent with fuel usage, but over time it may start to decline.

When you detect a change, it may be time to replace a filter or other components.

Your fuel injectors can become clogged or blocked open by contaminants. In the case of blocked open, that means the injector will consistently add more fuel into the combustion chamber than is required.

Your car will use more fuel than required for optimum combustion and your fuel consumption will go up (and mileage or economy goes down).

How to Fix It

A blocked or clogged fuel injector may be fixed by adding a fuel injector cleaner to the fuel tank the next time you fill the tank at the pump.

If that clears the contamination, you can then add cleaner frequently to reduce the chance of the injectors becoming clogged or blocked open in the future.

If a cleaning solution doesn’t fix the problem, the injector may need to be professionally serviced or replaced by a mechanic.

#9 – You Suddenly Have An Engine Hesitation Or Stumble

An engine hesitation or stumble is often caused by a lack of fuel. That may be due to a failing fuel pump, a clogged fuel filter, or blocked injectors starving the engine of fuel.

How to Fix it

A diagnostic tool may point you in the right direction to start researching why your car is hesitating or stumbling. Oftentimes it’s something simple like changing a filter that will fix a lack of fuel.

#10 – Your Engine Has A Rough Or Surging Idle

Another tell-tale sign of a fuel injection problem is a rough or surging idle. It may have no other effect on the drivability of your car, and it may not affect the fuel economy.

If you allow the idle issue to continue, it may get worse over time and morph into a larger problem like stalling.

How to Fix It

Idling issues can be caused by a lack of fuel or an issue with an air bypass solenoid. A lack of fuel as previously mentioned could be a problem with the fuel pump, fuel filter, or one or more injectors.

The lack of air at idle may be attributed to an air-bypass solenoid sticking closed or corrosion blocking the incoming air.

Read Also: Car Makes Grinding Noise When Idle & Driving Slow (6 Reasons)

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