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Engine Sputtering/Backfiring

#1

R

rch316

I have the following engine in my ride on mower https://www.engine-specs.net/briggs-and-stratton/40h777.html a 40H777 22HP V-twin and I can't get it running smooth. I have replaced the following with no success in fixing the problem. What am I missing?
  1. carburetor
  2. fuel pump
  3. fuel filter
  4. air filter
  5. spark plugs
  6. ignition coils
  7. added new fuel
I confirmed vapor lock is not the problem by taking fuel cap off as the mower was stalling after running it for 30 mins before replacing all of the parts above.

I did find that when I run the mower and disconnect either one of the spark plug cables from the spark plug the sputtering stops. Does this mean anything?

Here is video of the mower running:

Any ideas? Thanks in advance.


#2

Craftsman Garage

Craftsman Garage

I would try adjusting the valves.


#3

R

rch316

I would try adjusting the valves.
Thank you! That is a bit over my knowledge so I will have to send it to a repair shop for that.


#4

Craftsman Garage

Craftsman Garage

Or just look up a YouTube video-


#5

S

slomo

camshaft time?


#6

Craftsman Garage

Craftsman Garage

Hmm, I would say that's unlikely. It doesn't sound like they've had the case opened up.


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