28M707-1166-E1 trouble starting

wtjackso said:
Replace the carb. They are not that much money and all indications are for whatever reason, their is something defective internally with your current carb.
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It is $140 for the OEM carb. The Chinese ones I have tried before fail within a month or two, those are the cheap ones. The one that is on the mower now is an OEM one I bought a year ago. Worked great until last week when I went to mow.
 
micahmesser said:
Good Morning!

I have been struggling to get my mower to start properly without injecting either carb cleaner into the carb or gas directly into the chamber. What have I done to fix this issue?

  1. Cleaned the Carb (3x now) - this included removing everything from the bowl and tube, physically cleaning all the jet holes and using both carb cleaner and compressed air
  2. Replaced the intake manifold (small crack that eventually became a big one after removing carb)
  3. Cleaned chamber according manufacture instructions
  4. Checked cold compression (reads 100psi both without and with oil)
  5. Charged battery
  6. Checked teeth of flywheel
  7. Replaced magneto (Original was extremely rusty and the spark was a little weak)
  8. Checked spark plug gap (0.30) and resistance (resistance was within tolerance, 6,000 ohms I believe if my memory serves me right)
  9. Checked spark - sparking like a mad man
  10. Cleaned alternator ring of rust
  11. Replaced fuel line with new fuel line
  12. Dried out fuel tank and replaced with new non-ethanol fuel
  13. Drained all oil and replaced with new oil
I should note that I was able to get the engine to start on the second turn after cleaning the carb for the third time. It started right up but since then it won't start. This makes me think it is the carb but after so many times cleaning it, I am just not sure that is the issue. The carb was replaced two years ago with a Briggs and Stratton Walbro. When I cleaned the carb the first time there was some gunk in the carb but none of that showed up after the first cleaning.

Any suggestions?
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Sounds like the choke isn't completely closed, manually try to
 
SOLVED!!!!!

To everyone, thank you!

I found the problem. As some people indicated, it was the choke. In one of my removals, probably the first one, the linkage had slipped out causing it to basically "float". I feel like an idiot not checking this!


Half of the choke was hanging outside of the channel. Once I put it back in, it started right up no problem.IMG_20210922_183730.jpg
 
Amen Bert.

Engines start off the pilot or low speed jet. These use tiny pilot jets and clog easily. Same as the emulsion tube you showed in your pictures.

What you've shown looks clean. Need to clean what you haven't yet.

Hope you kept the original magneto. All you had to do was de-rust the mounting areas where the 2 screws go. This improves the ground to engine block allowing current/voltage flow. Course the coil could be shot too.

 
slomo said:
Amen Bert.

Engines start off the pilot or low speed jet. These use tiny pilot jets and clog easily. Same as the emulsion tube you showed in your pictures.

What you've shown looks clean. Need to clean what you haven't yet.

Hope you kept the original magneto. All you had to do was de-rust the mounting areas where the 2 screws go. This improves the ground to engine block allowing current/voltage flow. Course the coil could be shot too.

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I have the original, I will keep it just in case I need a backup.

However, after four good cleanings it was the linkage that was the issue. Turns out the choke linkage had come partially out of the slot it is supposed to slide in, causing the choke to not engage.
 
micahmesser said:
SOLVED!!!!!

To everyone, thank you!

I found the problem. As some people indicated, it was the choke. In one of my removals, probably the first one, the linkage had slipped out causing it to basically "float". I feel like an idiot not checking this!


Half of the choke was hanging outside of the channel. Once I put it back in, it started right up no problem.
Click to expand...

I had the exact same thing happen not long ago. Took me forever to figure out. Finally got it running and it threw a rod.
 
micahmesser said:
SOLVED!!!!!

To everyone, thank you!

I found the problem. As some people indicated, it was the choke. In one of my removals, probably the first one, the linkage had slipped out causing it to basically "float". I feel like an idiot not checking this!


Half of the choke was hanging outside of the channel. Once I put it back in, it started right up no problem.
Click to expand...
Excellent. As aggravating as it is one gets a lot of satisfaction in figuring things out on their own. As my dad used to tell me experience is the best teacher.
 
bertsmobile1 said:
The rngine starts using the IDLE circuit
The IDLE circuit has it's own jet and passage down the side of the carb
On some it is fixed and covered by welch plug
If that passage is not clear the engine will not start full stop
This is why most of the techs here ignore it when a poster says they have cleaned a carb
99% have not actually done it properly
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Assuming the throttle butterfly is mostly closed when trying to start it, then yes the idle circuit will be used but when the throttle plate is completely open under any operating circumstances then the main jet will be used because there is no airflow restriction being created by the throttle plate to form manifold vacuum and pull fuel through the idle ports. Since there is no airflow restriction, air will be passing through the venturi at a high speed, creating the vacuum which relative to the atmospheric pressure of the float bowl will push up fuel through the main jet into the emulsion tube and intake. At partially closed throttle plate positions both jets can work together, even at full throttle no load.
 
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