John Deere 318 Mower (Timing?)

[TobaccoRoad]

My mom's 318 mower has lost power. The first time I started it a week ago, it sounded like it was hitting on one cylinder. So yesterday I cleaned the spark plugs and started it again. It appeared to run fine. Then when I started to mow, it had low power. I mowed just a little to see how it did and then quit and went back to the shed. When I cut it off, it backfired. I also noticed that the engine seemed very hot for just a short amount of time running. This sounds like a timing issue to me. Wonder what Ma could have done to make it "jump timing"? How do you check/adjust timing...??? Or if it's not timing, any suggestions.

Thanks much,
Kevin

 

[atschirner]

Start with the basics. Are the cooling fins under the shrouds clear? Grass and other junk could be causing the engine to run too warm. What did the plugs look like when you had them out last weekend? They could indicate a lean condition on one or both cylinders. Junk in the gas or carb could be blocking the fuel causing a lean running condition with the throttle opened up. Either of these possible conditions could lead to the other.

As the old saying goes "if you hear hoof beats, look for horses, not zebras".

In other words, check all of the easy stuff first. Timing would be a long way down my list of possible causes for your problem.

Please let us know what you find. Feedback is always welcome.

 

[Acehardly]

What engine? P or B series?
If it is B series, check the points. They could be pitted, very easy to check.

 

[TobaccoRoad]

Thanks guys!!! The mower has an Onan Engine. The Model number is B456-GA01.

I found that the gas line had hardened and curled and was holding against the linkage to the carburetor. Not sure what you call this linkage that goes to a diaphragm type unit that controls the idle or rev of the engine when it goes under load.

Again, thanks much for having me check for the simple stuff first. I mowed the yard with no problem.

It did backfire again when I cut it off... Hmmm???

 

[atschirner]

TR, glad you got your mower running and thanks for updating us.

On your backfiring problem, are you turning the key off at idle or with the engine running at full governed speed? Try letting the engine idle for 15 or 20 seconds before you shut down. It could be that after you turn the key off the flywheeling of the engine is pulling fuel / air mixture into the muffler where it is combusting causing your backfire.

Have a safe weekend, Alan

 

[TobaccoRoad]

Hey Alan,

Yes, when I got the mower, I was told to always have it at full throttle when mowing, so I didn't throttle down before turning it off. I'll try that next time and tell Ma to do the same.


Thanks again team for helping!

Regards,
Kevin