Little Help With My Mower?

OK all you small engine gurus. The lawn tractor engine is "pulsating". I've seen it in other peoples equipment but now it's my problem. Can someone tell me what causes it and how to address it.

The plug and air filter are clean. I put on a new inline fuel filter after I blew out the lines. I don't know where to go from here. And what is that little black round thing mounted on the engine cover that the fuel is running through?

Thanks for any insight you may be able to give me

 

The black round thing is the fuel pump. The pulsing is most likely a clogged passage in the carb.

 

The first thing I try is about 3 oz of Sea Foam in a full fuel tank.

 

I considered that thing might be the pump but there aren't any wires to it and it's not connected to the engine for a mechanical type drive.

I just went out and put some carb cleaner in the tank. I left it running to give it a chance to work it's way into the system.

Looks like we posted at the same time.

 

It should run of the pulse of the piston similar to a chainsaw. Sometimes using gum cutter works. Start the tractor rev up and spray it in the carb the motor will try and die out but will pick back up.

 

OK. That explains the third line going in that isn't connected to the fuel supply in any way . Didn't think of it working the same way as a saw because of the size of the engine.

 

Yeah it is different. It could be other things causing it but cleaning the carb is easy and a good place to start.

 

It's a vacuum operated fuel pump. I have had to blow mine out with compressed air in the past.

 

I just went out and shut it off. I'll go out tomorrow and run it around the yard a few times to make sure the cleaner is mixed in well and has had a chance to get up to the carb.

Yep. Did that too. All I saw was gas spitting out; no obvious obstacles.

 

That's what my pressure washer was doing, seafoam fixed it right up, I have used it several times on small engines for an easy fix

 

Yep I am with MasterMech the low speed or idle circuit is plugged.

 

It does surge under load. Made it real interesting mowing until I decided to quit and have a look at it.

 

Yep. Pulling the bowl off is where I planned to start when I go back to it tomorrow. Hopefully after I run it around the yard a few times the cleaner will get in there and work it's magic. Then I won't have to do anything.

 

Fired it up this morning, ran around the yard a few times, engaged the blades and it was still surging. When I got back to the shed and idled it down it smoothed out. I wasn't expecting that. I ran it back up and it stayed smooth. Engaged the blades- still good. I guess the cleaner I threw in the tank last night worked it's magic.

Thanks everyone for your input. One can always count on the folks at FHC to share their wisdom.