Mercury Outboard Cranks But Won’t Start

Mercury Outboard Cranks But Won’t Start- What To Do Now?


Mercury outboard not starting is a common problem in outboards. Sometimes when you try to start it, it doesn’t start and starts cranking slowly. Before starting to make a call for professional help, look into some matters. You can probably solve it yourself. Wondering how?

We are here to walk you through the entire process!

So, why does your mercury outboard crank but won’t start? 

There could be more than one reason why the outboard is experiencing a starting complication. It could be a battery problem or an incorrect starting function. A fuel tank issue or a carburetor issue could also be a reason. In these cases, troubleshooting the outboard might fix it.

Now, you must be worried about how to do it step-by-step. No worries! We have mentioned all the guidelines here in detail to help you out. 

Let’s hop on the wagon and jump right in-

Why Mercury Outboard Cranks But Won’t Start- 8 Possible Reasons

Sometimes mercury outboard cranks but doesn’t start operating. There might be one or more than one reason behind this problem. Check out these factors in your mercury outboard to identify what is causing the trouble-

Reason 1: Battery Issue

One of the most common problems that mercury outboard faces are complications of a battery issue. First, check the battery state and make sure it is charged enough to start the engine. 

If it is charged enough but still not responding, then discharge it. Again recharge it and then try to start. You can also replace the battery if it’s not working at all. However, sometimes battery switches can cause the problem as well. So make sure to test if the switch is working or not.

Reason 2: Fuel Tank 

When the fuel tank is at its endpoint, the outboard won’t start. So ensure to fill your fuel tank appropriately before starting. 

Also, don’t use contaminated fuel mixed with water, dirt, etc. It will possibly cause starting complications. Yamaha Fuel pump problems in outboards often create cranks and faces starting difficulties like this.

Secondly, if the fuel tank vent is closed, the mercury outboard will start cranking and won’t start. So, make sure to lose the fuel line of your outboard and put the correct pump pressure. If any dirt is stopping the fuel flow, remove it from the filter as well.

We have mentioned some good quality fuels for mercury outboard that you can use to fix it.

Product 1
Product 2

 Reason 3:  Starting Failures

Sometimes, when you start the outboard in the wrong procedure, it fails to operate. Make sure you have correctly turned on the outboard. Check the battery and cable connections twice. The cable connection should be safe from corrosion. 

To save them from dirt and corrosion, you can lube the steering cables.

Another important thing you should check at the starting circuit is voltage drop. These activities will help to solve the starting difficulties of mercury outboard cranks. 

Reason 4: Valve Operation Failures

If you have already checked all of the facts mentioned above, it’s time to review the valves. Ensure that anti-siphon valves are working fine. Also, if the enrichment or choke solenoid valve is not operating correctly, the outboard will not start functioning. 

Reason 5: Faulty Carburetor

Last but not least, it could be the carburetors which are causing the problem. If there is an improper or restricted carburetor jet, the outboard won’t be able to start. 

These are the probable reasons behind your mercury outboard cranks, which aren’t allowing it to start. Now let’s move on to fixing it!

What To Do If Mercury Outboard Cranks But Won’t Start- Easy Solutions

After identifying the problem, the next step is, how to fix it. First things first, you have to download a repair manual to fix the issues. There are different manuals available for different models of mercury outboards. 

However, you will find the troubleshooting procedures of mercury outboards in the manual books. You can follow the troubleshooting guideline, except for the battery and fuel tank-related factors. As you can solve those issues on your own. 

And nowadays, there are more advanced techniques in the troubleshooting manual. To troubleshoot, firstly you have to make sure that the fuel tank is full. Secondly, check the fuel shut-off valve is open or not. Then frequently, check the fuel pump pressure, fuel filters and fuel lines. In case there is fuel leakage, fix it. 

Lastly, check the wires and carburetors. Ensure the fuel vent is open. And if everything is done as per the instructions, you can start the engine finally. 

Sometimes, if the outboard has been sitting for too long, it faces difficulties in operating. However, if any of these methods don’t work, you should call for professional help. 


Question: Why won’t the outboard motor go up?

Answer: If you can hear the motor running, but it isn’t going up. Maybe there is a leak, and hydraulic fluid isn’t evaporating. To fix the problem, try to trim the motor up and down and add some fluid. Then again, trip the engine up and down. By doing this, the outboard motor will go up.

Question: Is it safe to dry-start an outboard motor?

Answer: No, it’s not safe to dry-start an outboard motor. It can dry the water pump impeller. If you turn on the starter motor without activating the engine, you might get away with it for a while. So, don’t try to dry-start an outboard motor.

Question: Why is the outboard not getting spark?

Answer: If the outboard is not getting any spark, the reason might be the ignition key switch. To start an outboard, it needs to spark at the spark plugs. If there is no spark, check the wires carefully and the key switch as well. That can be the culprit of this matter.


That’s everything we had regarding what to do if mercury outboard cranks but won’t start. We hope we were able to help you find out the reason and solve the situation. 

Make sure to follow our instructions correctly while using the method.

Good luck with fixing the problem!

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