Mercury EFI Throttle Position Sensor Problems – How to Solve Them?

position sensor efi throttle

Facing problems with your Mercury EFI throttle position sensor? You are just where you need to be. Because we have just what you need.

By this time you’ve probably figured out there is an issue with the throttle position sensor. Nevertheless, you are unable to identify the exact issue at hand. Don’t worry you’re not alone.

But first, let’s address the mercury EFI throttle position sensor problem. What actually goes wrong?

A faulty mercury EFI TPS will result in multiple problems. Such as e reduced RPM and erratic voltage change. As well as an inability to monitor air intake. But these are solvable. The solution could be throttle cable adjustment, resetting, or replacing the TPS. And throttle cam to roller adjustment.

The entirety of this article has elaborated on each issue and its remedies. Additionally to any potential symptoms. So stay around.

Let’s begin!

Mercury EFI Throttle Position Sensor Problems Symptoms

The Mercury efi throttle position sensor doesn’t usually go bad. But if it occurs, there will be some obvious indications.

You should look out for these symptoms. If your jet ski is showing these symptoms, it’s probably because of the faulty throttle position sensor.

Here are some of the most common symptoms of mercury efi throttle sensor problems.

Mercury EFI

Symptom 1 of 3:  The Warning Horn Will Sound

The warning horn should emit if your TPS is malfunctioning.

You could easily panic hearing the warning horn. Be at ease, though! There’s no need to worry. As it isn’t as frightening as it seems

Symptom 2 of 3: Check Engine Light Will Illuminate

You could be worried because the check engine light is illuminating. What could that mean?

Well, the check engine light could illuminate because of various reasons. For example, if the engine doesn’t have sufficient engine fluid the light could illuminate.

Hence make sure to check for the TPS issues after changing the engine fluid. The mercury as well as the Mercruiser needs engine fluid change before going to the TPS

But generally, it illuminates because of throttle position problems.

Symptom 3 of 3: DDT will Indicate Failed TPS

You should check out the DDT. Because if you have a failed TPS then the DDT will indicate it.

So, if you get the feeling that you’re having a failed TPS do check the DDT for assurance.

Mercury EFI Throttle Position Sensor Problems

EFI throttle position problems are more common than you think. So if you’re facing such a problem you shouldn’t feel very unfortunate.

Almost every other jetski owner faces this problem at some stage. It’s one of the most common jet ski problems.

So, what are actually the problems that could occur because of throttle position?

We’ve elaborated on it in your next segment.

Mercury EFI Throttle

Problem 1 of 3: Voltage Change will be Erratic

Now could be facing erratic voltage changes. Well, erratic voltage changes could occur because of multiple reasons.

But it mostly occurs because of faulty throttle sensor problems.

So, if you’re facing erratic voltage you don’t need to worry. It’s happening probably because of the position throttle problem.

Problem 2 of 3: RPM will be Reduced

You’ll frequently see reduced RPM as a result of a malfunctioning TPS.

The reason behind this is the throttle sensor affects the Engine Control Module (ECM). Because of this, you’ll find RPM will not increase. It is reduced.

Hence, if you’re facing reduced RPM it’s probably because your throttle position sensor is faulty.

This could also result in the boat going under 2000 rpm under load.

Problem 3 of 3: Can’t Monitor Air Intake

A TPS’s main responsibility is to keep track of the air intake.

As a result, when the sensor becomes defective it fails to monitor the air intake.

Mercury EFI Throttle Position Sensor Problem Solutions

When there is a problem there must be a solution. So don’t worry if you’re facing throttle position sensor problems. Since we have also developed solutions to the issues we’ve listed.

So, without missing a beat, let’s begin addressing your issue.

Solution 1 of 3: Adjust the Throttle Cable

The first thing you need to do is to check the throttle cable adjustment. The throttle stop screw should be in a particular position when the engine is started.

You’ll find the throttle stop screw on the throttle on the arm. This screw ought to be resting on the cylinder block’s throttle stop.

If required, preload the throttle cable barrel by one or two turns.

Solution 2 of 3: Reset or Replace the TPS

You may only need to reset a defective TPS occasionally. You could consider this as the Mercury efi throttle position sensor adjustment.

Disconnect the battery’s negative cable in order to reset the TPS. And then leave it disconnected for 5 minutes. Or you could just remove the fuse from the engine control module.

This should reset the Mercury EFI throttle position sensor.

However, if the TPS is still not working you better replace it.

Do check these out. If you want to purchase a new one.

Once you have a new TPS all you need to do is first locate the TPS. Then disconnect all the wires from it. Then unscrew the bolts to take it out.

Then after taking it or just place the new one in the older one’s place.

And that’s how you can replace the Mercury EFI throttle position sensor.

Solution 3 of 3: Adjust the Throttle Cam to Roller

Then comes the throttle cam to roller adjustment. It is necessary to have a perfect cam to roller adjustment.

Hence, for this, you need to troubleshoot the cam to roller adjustment. This is going to help you in the long run.

The roller could be shifting its position on the cam. It might oscillate in the cam. It happens if the roller is not sitting on the pocket area perfectly.

This affects the TPS link arm. It causes it to pull or push on the lever that is on the TPS. This results in a change in values.

Thus, to avoid this, the adjustment of the throttle cam to the roller should be checked.


Mercury EFI Four Stroke

When did Mercury introduce fuel injection?

Mercury introduced its first fuel-injected outboard motor, the Mercury 175 HP EFI, in 1985.

This was a significant development in the marine industry, as it allowed for more efficient and precise fuel delivery to the engine, resulting in improved performance and fuel economy.

Since then, fuel injection has become a standard feature on many Mercury outboard motors, and has been adopted by other manufacturers as well.

When did Mercury introduce their 4-stroke outboard?

Mercury introduced its first 4-stroke outboard motor, the Mercury 25 HP 4-stroke, in 1998.

This was a significant milestone for the company, as it allowed them to compete with other manufacturers who had already been producing 4-stroke motors for several years.

The 4-stroke technology offered several advantages over traditional 2-stroke motors, including lower emissions, better fuel economy, and quieter operation.

Since then, Mercury has continued to expand its line of 4-stroke outboard motors, with models ranging from 2.5 HP to 400 HP.

Where is the throttle position sensor located?

The location of the throttle position sensor (TPS) can vary depending on the make and model of the engine.

In general, the TPS is located near the throttle body, which is typically mounted on the intake manifold. On some engines, the TPS may be located on the throttle pedal assembly or on the throttle linkage itself.

The TPS is a crucial component of the engine management system, as it provides feedback to the engine control module (ECM) regarding the position of the throttle.

This information is used to adjust fuel delivery and ignition timing to optimize engine performance and fuel economy.

If the TPS fails or malfunctions, it can cause a range of issues, including poor acceleration, rough idle, and stalling.

What causes an outboard motor to bog down at full throttle?

There are several potential causes of an outboard motor bogging down at full throttle. One common issue is a clogged fuel filter, which can restrict fuel flow and cause the engine to run poorly.

Another possibility is a dirty or clogged carburetor, which can result in a lean fuel mixture that causes the engine to bog down under load.

Other potential causes include a damaged propeller, a malfunctioning fuel pump, or a faulty spark plug.

In some cases, the issue may be related to the boat itself, such as improper weight distribution or an overloaded vessel.

It’s important to diagnose the cause of the bogging down and address it promptly to prevent further damage to the engine or other components.


By now you should have a clear idea of Mercury EFI throttle position sensor problems.

But if the sensor problem persists then you should consult a professional. Because you risk damaging your engine if you don’t understand exactly what you’re doing.

That’ll be all from us. Catch you another time.

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