How To Detect A Bad Fuel Pump On Mercury Outboard?(Explained)

If you encounter a bumpy ride or the engine suddenly stops while riding a mercury outboard, most probably the problem is in the fuel pump.

This article will help you to detect a faulty fuel pump on a Mercury Outboard and how to fix it-

Sign Of A Bad Fuel Pump On Mercury Outboard

The earliest and easiest sign of a bad fuel pump on mercury outboard is rapid usage of fuel than usual.

Overtimes, every user gets a precise idea of how long the fuel will last when the tank is full.

However, when you notice that the fuel is finishing faster than standard, that is the first sign of a bad fuel pump.

Common Mercury Outboard Bad Fuel Pump Symptoms

The symptoms of a bad fuel pump are usually similar to the below-stated indications:

1. Rapid Fuel Usage:

Sometimes knowing how long a 100% full fuel tank will last during your ride on mercury outboard does not come in handy especially, while going to remote job site locations.

Because people often experience that the fuel is draining faster than natural, which is a clear sign of a deteriorated fuel pump.

2. No Sound Or Noise When Engine Starts:

Generally, the engine or motor of the Mercury outboard makes a noticeable sound or noise as the fuel pump gets engaged.

But if you ever notice that there is no familiar noise while starting the engine, it is another significant indication faulty fuel pump.

3. Sputtering, Misfiring Or Bumpy Rides:

Sputtering or misfiring is another common symptom which also causes the engine to die.

While you are riding in high-speed motion, if the speed abruptly slows down or the engine stops running all of a sudden, it indicates that the fuel system has an issue.

It mainly happens because the pump stops providing constant fuel, even though the fuel gauge indicates complete fuel efficiency in the tank.

4. Temperature Rises:

Another noticeable symptom of having a faulty or bad fuel pump is when you see that the temperature of the fuel gauge is unusually rising.

It mostly happens when the fuel pump fails, so it is better to check on your whole fuel system whenever you notice that.

If you ever experience any of these mentioned symptoms, make sure to have the whole fuel system check-up to fix the issue.

How Should You React If You Detect A Bad Fuel Pump?

If you detect any of those symptoms mentioned earlier, remember to act calmly but quickly.

Here are the five easy and efficient ways to fix the problem-

Pour Correct Fuel Mixture:

If you have mercury onboard two-stroke engines, it requires a specific fuel mixture containing particular marine oil and gasoline.

If you have not mixed the fuel correctly like 32:1, 40:1, or 50:1 based on the model you have, empty the fuel tank and mix clean gasoline with oil according to your model’s instructed ratio.

Inspect Kill Switch, Gear & Gas Tank:

Check whether the kill switch is attached properly or not. If not, undo the connection and put it back into the right place accordingly.

If the kill switch seems faulty, you need to replace it. Also, make sure that you have gear on neutral before starting the engine.

If you have already checked the fuel level and it is full, check whether the gas tank vent is open or close and make sure it is open.

Check The Battery & Fuel Filter:

Some Mercury outboard engines have batteries to start the engine except the pull-start type.

So, if your engine is not the pull-start one, make sure that the battery is clean, connections are on point, and charged enough.

Check on the fuel filter whether there is any blockage or clog issue. If the fuel filter is blocked or clogged, you need to clean or replace it.

Fixing Ignition System & Spark Plugs:

Inspect whether the ignition system’s spark plugs are damaged or dirty.

If spark plugs are damaged, then you need to replace them. If the spark plugs are dirty, then remove, clean them neatly, and set them back in place.

Now check the ignition spark with a spark tester, and if the spark is good, ensure the air gap specification as needed.

Lastly, turn the ignition to the “On” position.

Perform Test On Fuel Pump:

If none above-mentioned issues caused damage to your fuel pump, then do a proper inspection.

Turn the engine off, then remove the cowl cover, spark plug wire boot, and the plug to check the compression gauge reading, whether the reading shows is under 30 PSI or above.

If it shows under 30 PSI you need to change the compression gauge.  Besides the compression issue, it can be caused by a diaphragm or one-way valves.

You can do the test by removing the fuel pump from the engine. If the problem is in one of them, you need to replace that faulty part.

Is Replacing A Bad Fuel Pump Typically Expensive?

Honestly, it depends on the damage level of your fuel pump. If there are temporary fixing issues and you know how to fix them, it will not cost you much.

If the problem does not solve after doing temporary changes or fixing, you should contact your dealer or servicing center to fix or replace it.

However, in general, the high-pressure pump can cost around $480, and other required stuff like a gasket, seals, etc. may cost approx. $35. The labor costs will vary too based on the damage condition but it will be around $135 per hour.

How Often Should You Inspect Or Service The Mercury Outboard Fuel Pump?

The easiest way to avoid having a bad fuel pump is to perform the required regular engine maintenance and frequently stabilizing the fuel.

Generally, all mercury outboard users are advised to inspect and service the motor, windshield wipers, and water pump impeller every once a year or 100 to 200 hours of operation.

Also, those who own the mercury outboard newer engines are instructed to do the servicing every 50 hours of operation.

Final Thoughts

The best way to avoid bad fuel pump issues is to maintain regular motor and other essential parts. Also, frequent fuel stabilizing will increase your engine’s longevity.

However, keep an eye on your outboard, whether it shows any signs mentioned in the article, and act fast to resolve the problem.

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