OT - Honda lawnmower problem and fix

Was it the original plug?

Maybe. She took it to the dealer once & they might have replaced it, or not.

It was pretty dirty/sooty, so maybe that was the problem. I should blast clean it and try it.

Yes, spark plugs can fail in strange ways.

I once had a car where one cylinder would stop firing when I added lots of throttle. It was very impractical when trying to overtake. It was the spark plug.

A new plug is high on my troubleshooting sequence, after cleaning the air filter. It helps often enough to justify buying a few spares in advance.

Replacing the HF genny's plug didn't help, although I found it gapped below spec. The NGK equivalent lacked the needed sleeve that screws on the terminal stud, a reason to save a few from old plugs.

I didn't trade it under warranty for a new one because the older 2200W HF 61169 outputs a confirmed 18A while the newer 1600W 62523 model is rated at 13A, and I may need both the fridge and A/C during a summer hurricane power outage. Hopefully both won't try to start simultaneously while I'm asleep or out cleaning up.

I read that the gel that accumulates in carburetors is aluminum hydroxide corrosion from water in the ethanol. The only solvent for it I know of is too caustic to use. While searching for info on the HF carb I read the manuals for Honda inverter generators whose idle "pilot" adjusting screws break at the neck-down and must be replaced when removed to blow out the passages.

-jsw

I cleaned it and the mower ran!

But it needs some choke, even after it's warm. Probably why the plug was so dirty. These things don't have mixture adjustment, unless you break a security screw. That's next.

OMG. Honda uses NGK

Why? Blast cleaning is no longer recommended - too easy to get a grain of blast medium where it doesn't belong - doing expensive damage - and plugs are CHEAP!!!

Ethanol gas will require choke to make it run right in many cases - also sometines passages are restricted but not plugged - running a dose of Sea-Foam in the gas often solves the latter.

NGK isn't a BAD plug, but I always found the equivalent NipponDenso was a better bet back in my Toyota days

If someone finds gel in their carb bowl it would be useful to see what if anything dissolves it.

-jsw

I did clean the carb with carb cleaner, before I Google told me about the spark plug. Sea-Form couldn't hurt, so I'll try that 1st.

Thanks

I do already have a new plug. The blasting was to see if the soot was the problem.

You bet. My late father had given me a, virtually brand new, lawn trimmer that wouldn't run more than a few sec. I had gone over it with a fine tooth comb, everything seemed correct. Ran great, when it would run. It was a bad spark plug.

It's your dime, and your time - but you already KNOW the plug was the problem - if you want to know if it was carbon, just wash it with laquer thinners and bake it untill it's white. I do it with my torch - just heat it up with the propane torch until the porcelain tip glows then keep it in the envelope of the flame for a few seconds - comes perfectly clean - and USUALLY restores the function of the plug. Years ago with leaded gas sometimes it would have a yellow or green "glaze: on the insulator that would not burn off, or blast off. Some product of sulpher and lead catalyzed by the silica in the insulator - I believe it was lead sulphide (Germanium) - basically a cheap semiconductor

When I was in trade school part of my class inherited an F head Jeep engine that had been rebuilt by the previous class and it would not atart. ASfter a couple weeks I said it can't be rocket science - the engine is totally rebuilt - it HAS to run. For opening my mouth, I was put in charge of getting it started. Within 15 minutes I had pulled the previously cleaned plugs and replaced them with another set out of the pluf box, and had it running. There was more that needed fixing to get it driveable - but the plugs solved the start/run problem.

Not to pick on you, but lead sulfide is Galena, the semiconductor used for early "cat's whisker" radio detector diodes.

You are right. I was wrong - but it was STILL a cheap diode - and as a semicinductor it had a very detrimental effect on the spark - - -

You never know what will become a True Fact after someone with a good reputation like yours posts it here.

Sulfur is an unavoidable contaminant of petroleum products. The cure is adding phosphorus to bind to the lead in your 100LL.

-jsw