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Trouble Shooting Nissan 5A 4 stroke

P

PacificSailors

New member
I have a Nissan 5A 4 stroke engine with 2000 year emissions tags.

The problem is that every now and then it will cut out and usually die. I have always had to pull the choke out to start it. When it does act up and I restart the engine I pull the choke out about halfway, let it run for a couple of minutes then push the choke back in, and it runs for awhile. Usually the engine will then run for up to a half hour or so with no problems, then suddenly die again.

What I have tried already...
1.) Emptied all of the old fuel and replaced with fresh and a some gas treatment that I have always used. I am in Puerto Vallarta Mexico and I am very diligent about keeping fresh fuel and treating for water in the fuel. I have a honda generator and it's running fine using the same fuel as the outboard.
2.) Checked the spark plug.
3.) Cleaned up the carb.

Any thoughtful ideas on how to fix would be greatly appreciated.

Thanks,
Mike
 
You probably have either an ignition or fuel problem. Most common is fuel system.

What did the old plug look like?

Do you always run the carb out at the end of each and every day? If not, you may be seeing some varnishing in the carb, which can only be removed by a thorough soak.

What method did you use to clean the carb? A complete disassembly and a 4-hour soak in real carb cleaner is the only sure way to get one clean.

You can run analog ohm meter tests on the ignition system. You can also check for delivery pressure and vacuum of the fuel pump.

If you are developing vacuum in the external tank, such as from a closed or clogged vent, the fuel pump may not be able to draw well enough to overcome the vacuum. Likewise, if an o-ring in the primer hose is leaking air, the pump will draw air into the system (because it's lighter and lower "viscosity" than fuel) unless the tank is higher than the motor, and is being assisted by gravity.
 
Thanks for the reply Paul. Funny the spark plug appeared to be in excellent condition. Look at some of the spark plug analysis charts and it is the epitome of normal and the electrode is not worn down at all. I replaced the plug and the engine runs like new again, I ran the engine for about a half hour yesterday with not so much as a sputter. I believe that I may have found the fix.

Mike



pvanv said:
You probably have either an ignition or fuel problem. Most common is fuel system.

What did the old plug look like?

Do you always run the carb out at the end of each and every day? If not, you may be seeing some varnishing in the carb, which can only be removed by a thorough soak.

What method did you use to clean the carb? A complete disassembly and a 4-hour soak in real carb cleaner is the only sure way to get one clean.

You can run analog ohm meter tests on the ignition system. You can also check for delivery pressure and vacuum of the fuel pump.

If you are developing vacuum in the external tank, such as from a closed or clogged vent, the fuel pump may not be able to draw well enough to overcome the vacuum. Likewise, if an o-ring in the primer hose is leaking air, the pump will draw air into the system (because it's lighter and lower "viscosity" than fuel) unless the tank is higher than the motor, and is being assisted by gravity.
Click to expand...
 
I too have found defective plugs that looked OK, but had issues. Usually insulation problems that could not be seen with the ***** eye. Hopefully you got it!
 
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One thing you may check is the kill switch. I had the same problem. The kill switch had a short and would intermittently kill the engine. you can test by just disconnecting the wire from the ignition coil to the switch.
Good Luck
 
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