Need help, lawn mower suddenly backfiring and no power

[branfarm]

Hello experts, looking for some of your small engine wisdom.

I have a 12 year old Honda hrx217hka with the gcv190 engine. Over the last few years it's steadily gotten harder to start (1-pull starts turned into 8+ pulls). I replaced the carb, spark plug, filter and oil last year on my own. It didn't help, so I took it to a small engine shop they gave it a once over with some "minor tune ups" and I was able to get it started in 2-3 pulls through the end of the season.

This year I figured out that if I push hard on the throttle when in the choke position, I can get it start in 1 or 2 pulls. Well last week I was mowing and after about an hour the machine suddenly started sputtering, backfiring, and losing all power when I engaged the blade. I recorded this video right after it happened:



I went out this evening to give it another shot, thinking maybe it was just overheated last week, and it immediately started backfiring. I recorded this a few minutes ago:



Same basic symptoms -- backfiring, sputtering, sounds like it's going to die then manages to come back to life.

Would anyone have any pointers on things I can look at to further troubleshoot? I love my mower and don't want to let the ol' girl go.

 

[Nukeman7]

I would check the valve clearances on the Honda OHV motor. Backfiring and sputtering suggests that the lash clearance may be out of tolerance and needs adjustment.

 

[fantastic]

I'd start w/what @Nukeman7 said with the valve clearances. Find the correct clearance values w/some feeler gauges. If that fails it may be time to take the head off to inspect. Do the clearances first then get a rpm measuring tool to set the carburetor up correctly first as it may be too rich. Give it good cleaning at least since they're easy to remove. Spray carb cleaner down every hole. If none of that fixes it then it'll be time to remove the head to see what valve train problem you may have.

 

[doitmyself]

That engine has a timing belt and plastic camshaft that can be the point of bad timing. Here's a start:

 

[doitmyself]

The very basic diagnosis of engines is that there are 4 systems to check:
1). Air/fuel (carb, fuel, fuel filter, tank/cap vent, plugged muffler, etc.)
2.) Spark (plug, electronics, etc.)
3.) Compression ( valves, piston rings, etc.)
4.) Timing (flywheel key, camshaft-timing belt, etc.)

You start with the very easiest (1 and 2) and move on to 3 and 4. With each of those 4 systems, there are LOTS of possible issues. I.E., a loose carb/bad gasket can allow extra air to leak in to mess up the fuel mixture. Bad cable linkages, and on and on.

Good luck!!!!

 

[nate379]

Clean the carb

 

[ripcord]

Have you ever hit a stump or big rock with the mower? If yes, you may have sheared the timing key that connects the timing wheel to the crankshaft.

The higher probability solution, though, is adjusting the valves as was mentioned before.

 

[Snagglefoot]

I would check the valve clearances on the Honda OHV motor. Backfiring and sputtering suggests that the lash clearance may be out of tolerance and needs adjustment.

The valve cover will need to be removed. On that model it is sealed with black RTV. You need to cut it with an exacto knife or other blade to get it off. You might want to order a new cover with the built-in belt guide if it doesn’t have one. You use feeler cages to check the clearance. There are some good You Tube videos out there.

 

[ripcord]

Line more thing... Remove the spark plug before turning the engine over while adjusting the valves. You don't want to accidentally pop start the engine even though the mower has a blade brake.

 

[Hirev]

Cover the basics 1st. Drain the carb bowl in case there is water in it with the gas. This gets a lot of small engines. There also could be debris in the main jet.

OEM spark plug? Years ago my honda mower started acting up. It than died and would not restart. I had a new OEM spark plug around checked the gap threw it in all was good again.

 

[zzyzzx]

All good suggestions, but add in the possibility of head gasket issue as well.

 

[wag123]

You have a carburetor problem. A sticky choke will do what you are describing, not closing all the way will cause your starting problem and not opening all the way will cause the run problem. A restricted air bleed in the carb can also do this.

 

[DriveHard]

You have a carburetor problem. A sticky choke will do what you are describing, not closing all the way will cause your starting problem and not opening all the way will cause the run problem. A restricted air bleed in the carb can also do this.

This was my first thought as well...especially if it is all of a sudden. While valve clearance might be it...it would be lower on my inspection list.

 

[wavinwayne]

I had the exact same issue with a pressure washer a few years ago. My FIL diagnosed and fixed it. It was carb related, sorry I don't remember what exactly the carb issue was. I would start with the carb.

 

[loneryder]

Corn starch in carb and bowl from ethanol gas even though it’s a recent carb.

 

[JohnnyG]

Here's a good rule to follow, and it's pretty universal:
Backfiring through the intake (carb) indicate too LEAN a mixture, Backfiring through the exhaust indicates too RICH a mixture.

In your case you can even see the flames from the excess fuel igniting in the muffler.
Of course if timing is wrong, it could be that as well.

 

[E150GT]

The only time my honda backfired is when the carb was dirty but it would start and to keep it running I had to force the choke closed at all times. It would run but it backfired like crazy

 

[The_Eric]

I doubt that it's an ethanol related issue. Those tend to make them run lean.. That one sounds either pig rich or maybe has a valve clearance issue.

 

[branfarm]

Thanks for the input everyone. I only use non-ethanol gas in the mower, but the carb sounds easier to deal with first than the valves so I'll start there.

 

[oilcandave]

I've had some come thru here with a skipped tooth on cam belt inside motor. While yer checkin valve clearance make sure the cam is still timed correctly. After the first one came thru here and did all of the above still was off. Checked cam timing and was out by one tooth.