Any small engine experts out there?

Sending this to LuckyGuy.

I’m probably a great deal more familiar with electric motors over internal combustion engines, but I’m familiar enough with them where I think I can somewhat help you. It definitely sounds like a backfire originally occurred, causing the flames to shoot from your exhaust along with the loud pop. Backfires should not damage your engine though, so I wouldn’t sweat that issue out.

There are several things that can cause engine backfires, but with your washer being new my bet would be either carburetor problems, or your carburetor may need to be correctly adjusted.

Have you drained the gas tank when you stored it away? If not there maybe a water and varnish issue in tank and carburetor.

I agree with @Tropical_Willie . Check the fuel filter, sometimes a slime will occur and plug it up. Slime comes from bacteria growing on the fuel/water interface in the filter element, due to moisture in the fuel. But it sounds like a little dirt in the carb. (fuel system)

If you failed to put some oil in the cylinder and then screw back in the spark plug before putting her away for the winter, this might be your problem.

Thanks for the helpful ideas.

I did run the engine until the fuel ran out before I stored it but I failed to remove the spark plug and pour “about a teaspoon of clean, air-cooled, four cycle lubricant through the spark plug hole into the combustion chamber” as directed to do in the storage maintenance directions. My bad.

Let us know what they find. I still think you’re having either timing or carburetor problems. Varnish clogging carburetor ports will simply either keep the engine from starting, or struggle to start and cause it to stall. Lubricating the combustion chamber is simply for lubrication purposes. A backfire is a misplaced combustion, so I’m basing my opinion off of this fact.

The fact that your engine ran good even for a short time tells me the lubrication thing isn’t even an issue here since it would get naturally lubricated once the piston is moving. This would only be an issue for initial starting purposes, and would not cause backfiring. The varnish issue would not cause backfiring either.

I could be wrong, but it’s my semi-professional guess, and has been my own experience working on various types of small engine powered equipment.

@Paradox25 They are backed up now and it will be a week before they have a chance to diagnose the problem.

I’ll let you know what they tell me. I was also thinking that failing to lube the combustion chamber prior to storage was not likely an issue here because the pressure washer was functioning perfectly (I went through nearly 2 tanks of gas) prior to suddenly not functioning.

@Paradox25 FYI: They replaced the cylinder, piston, ring set, flange N, clip (13mm), oil seal and oil. Total cost $418.88 paid for by Ryobi. The Honda engine was a major influence on me buying this pressure washer and is the last thing that I thought would break. Oh well nothing is perfect. C’est la vie!

The other problem would had been a bit cheaper to repair, but you had a warranty anyways.