FR651V surging after running out of fuel

[mikear]

I ran out of gas on my FR651V while mowing. I filled it with brand new non-ethanol gas (purchased that same day). The mower now surges at all throttle positions except full throttle. Note that the mower ran flawlessly up until running out of fuel. At full throttle, I can mow without issue. I can feather the choke to clear up the surging at lower throttle positions.

Things I have tried:
- Replaced fuel filter
- Checked fuel lines for obstruction/collapse (none)
- Removed tank fuel tube to check for obstruction of the suction screen (none)
- Checked for adequate fuel pump outlet flow (good). Also cleaned pump vents.
- Cleaned carburetor, removed main jet and nozzle (small debris in bowl, no other obstructions noted, no improvement)
- Checked for missing Welch plugs on carb (all there)
- Removed Welch plug and adjusted pilot air screw in and out (no change)
- Removed fuel tank cap while surging (no change)

I’m going to get some new gas from a different station and run off an aux fuel supply. Next is to throw some parts at it like a fuel pump and new vacuum line, which I hate to do without logic. Again, I have no indication that the pump is failing but merely grasping for straws.

What am I missing? Thanks in advance

Mike

 

[Joed756]

The gas you just bought could have some water in it. drain some from the bottom of your tank into a clear container and let it sit for a few minutes.

 

[mikear]

The gas you just bought could have some water in it. drain some from the bottom of your tank into a clear container and let it sit for a few minutes.

Replaced all hoses from the tank to the carb (including the fuel pump pulse line). Tried an alternate gas source, both of which did not improve the situation.

A family member has a Kawasaki with the same fuel pump so I swapped mine with his. Also the same result.

I’m planning to take the carburetor back off and clean it once again, focusing on the pilot system.

Thanks for the suggestion.

 

[mikear]

Alright, problem solved. Removed the carb again and re-cleaned. Once it was clean, I cleaned it some more, followed up with compressed air. I paid particular attention to the pilot system. My assumption was when I ran out of fuel, I pulled a piece of debris from the bowl into the pilot jet that I missed during the first cleaning.

I figured a fuel passage in the pilot system had to be clogged when I fully closed the pilot/idle mixture screw and there was no change in surging whatsoever.

Thanks again.

 

[slomo]

Alright, problem solved.

Nice work getting her going.

Removed the carb again and re-cleaned. Once it was clean, I cleaned it some more, followed up with compressed air.

Sometimes you have to do this.

I paid particular attention to the pilot system.

Highly over looked. Nice catch.

My assumption was when I ran out of fuel, I pulled a piece of debris from the bowl into the pilot jet that I missed during the first cleaning.

Can happen anytime. Install a good filter and cross your fingers. Could of pushed some trash further into the carb as you are saying while cleaning.

Most 1/4 inch cheap push mower filters don't seal off 100%. You can shake most of the clear ones and the paper element will rattle in the housing. No wonder they are cheap and we get trash in the carbs. Always looking for the best out there. Nice to see someone test these mower filters with varying sizes of grit. See what passes and gets caught.

 

[7394]

Thinking last bit of gas sucked up had a bit of dirt in it.