28M707-1166-E1 trouble starting

[micahmesser]

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?

 

[Rivets]

When you cleaned the carb, did you do these two things? One, remove the main nozzle and make sure all the jets were open? Two, replace the float needle and seat, plus set the float level? Without doing #1 and possibly #2 you will be fighting a loosing cause.

 

[Scrubcadet10]

did you check your float level?
I believe this is the correct carburetor......

Disassembly, Cleaning and Repair of Walbro LMT Carburetor used on Briggs and Stratton Engines

outdoorpowerinfo.com

 

[micahmesser]

I removed the float, main nozzle, all of it. I cleaned them all out. The float moves freely and gas fills the carb but doesn't flood.

 

[Rivets]

Just because it seals properly doesn’t mean that it is at the proper height. If you didn’t set the float level properly, it may be set too low causing a lean starting and running condition.

 

[ILENGINE]

Have you checked to make sure the choke is closing completely. Just a little gap of not complete closing can causing starting issues.

 

[micahmesser]

Just because it seals properly doesn’t mean that it is at the proper height. If you didn’t set the float level properly, it may be set too low causing a lean starting and running condition.

My float doesn't look like it has any adjustment. The float is plastic, even where the needle sits in the float. Not sure how I would adjust it...

 

[micahmesser]

Have you checked to make sure the choke is closing completely. Just a little gap of not complete closing can causing starting issues.

It appears to be closing all the way. I have also tried starting at different levels of choke to no avail.

 

[micahmesser]

Did some more research. These plastic floats cannot be adjusted. What can happen is the needle gets worn and doesn't stop fuel from flowing into the bowl, thus causing flooding.

I took the carb apart a fourth time and cleaned it a fourth time. I attached pictures to show the bowl, main jet, fuel jet, etc.

I tried to crank it, no change. It just turns over and over without even giving a hint of starting. I sprayed a tad bit of carb cleaner into the air filter intake and it roared to life just fine. Fuel is making it into the carb bowl - that is not an issue. As you can see from these pictures, when I took it apart, a lot of fuel came out. I also tried without the air filter on, with the air filter on, gas cap on, gas cap off, etc. No change.

For some reason, the mixture is not rich enough to cause combustion to occur.

 

[bertsmobile1]

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