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Doug E.
Doug E., Kawasaki Master Technician
Category: Small Engine
Satisfied Customers: 2886
Experience:  Professional mechanic since the late 70's on Kawasaki, Arctic Cat, Jonsered, John Deere and others.
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I have a john deere 316 with an 18hp Onan engine. My friend

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I have a john deere 316 with an 18hp Onan engine. My friend took it apart last year and practically rebuilt it. The engine ran like a dream. after sitting this winter I start it and I have to choke it about 3/4 of the way out to get it to run smooth. I've taken off the aire filter and top piece and tried to adjust it the carburator on the front. Left or right 1 to 2 turns seems to do nothing. I took off the filter and blew it out and it seems good. It was a new filter back when it was torn down. Any ideas on what can be causing it to run rough. It runs like it's running out fo gas and then picks up over and over until you pull the choke out.

Doug :

Hello

Doug :

It's very common to have problems with the gas going bad and turning to a gum or varnish. This takes about 2 months, so is a major problem in machines that are not run year round. You have a lean condition which requires that you use the choke to keep the motor running. If it were a fuel pump or fuel delivery problem, the choke wouldn't help.

Doug :

You can try running SeaFoam in the gas to see if it will dissolve the varnish, but there is a very good chance the carb will need to be pulled, taken apart and soaked in carb cleaner to correct the problem.

Doug :

I use non-ethanol premium fuel with SeaFoam in my vintage JD mower all the time. That way if I don't run it for a few weeks or a month, I know it will not be a problem.

Doug :

Do you know which model carb is used on yours?

Doug :

Some of them come apart from the top and it's easy to pull the carb apart and get to most of it without removing it.

Customer:

not sure which one I have. I saw some people talking about seafoam on another website and had no idea that is what is was. So just pull the carb ans soak it. Will the seafoam treat the gas or should I remove all of it?

Customer:

There is a little screw on the front of the carb. Do you know what that is for? it has a spring behind it and is perpindicular to the carb.

Doug :

That could be one of the jets. Turn it counter clockwise to make it richer, clockwise to make it leaner. If moving that has no effect, then you will have to clean the carb. It might also be the drain screw for the bowl if it's very small. If you turn it out and gas comes out, then it's the drain. You can drain the bowl using that to see if it helps. Sorry I don't know for sure if it's a jet or drain. I would need the numbers off of the carb in order to give you detailed information on it. I can come up with diagrams and more info if you can get me that. There were several carb models used. SeaFoam is available at any auto parts store. Just pour it in the gas tank per the ratio on the side of the can.

Doug :

I would remove all of your old gas if you still have some in the tank. Drain the carb. Fill with fresh gas with double the amount of SeaFoam as the can says and try running it for a half an hour or so. That may dissolve the varnish and get you going without taking the carb apart.

Customer:

will do thanks for the advise.

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