Lawn mower

[MF294-4]

Have a relative new push mower with a b/s engine. It will run about 15 min then die, prime it and it will run another 15 min.,repeat, cleaned tank,checked fuel cap. It will sit and run a tank of fuel without quitting. Something to do with putting a load on the engine? I have shook it and almost had it to a 45 and it will not quit on a test. Wife is at my pocket book to get a new one. Any ideas other than hers?

 

[Russ from MN]

First thing I would do is put some Seafoam in it, it might fix it! Also check the vent in the gas cap, I had one plugged recently, acted a little like yours. If that doesn't work take the bowl off the carburetor and clean out the jet and any other small passageways you can find.
You might get more responses on the garden tractor board.

 

[Steve@Advance]

Just to say you did, replace the spark plug. I know it sounds crazy, just do it! BTDT

Try taking the bowl off the carb, see what kind of flow you get through the needle valve. If it's a plastic carb, you may have to take it off to get the bowl off, but put the carb back on without the bowl, see what you get. should be a good stream, not a drip.

Sounds like a fuel restriction, enough getting through to run without a load, but once the load demand asks for more fuel, it's not there.

 

[gary49]

You might try pulling the tin off the motor, Ive had some weird things happen due to rodents building nests and compromising the cooling. Might be just enough cooling with no load for it not to overheat, but not enough cooling under load.

 

[Stephen Newell]

I think I would check the fuel line for a leak. Sometimes they don't actually leak fuel but the engine will suck air.

 

[SDMike]

MF294-4, I have seen 2 push mowers recently that the governor spring has come unhooked. Mower will idle fine, but as soon as it encounters a load, it will die. One was a cub cadet push and the other a husqvarna push. Had to pull a plastic cover off to see it, but it was right there.

Good Luck. Mike

 

[3000OH]

My brother called me just last night with a story about a newer lawnmower that he got from his neighbor who gave up on it. It would run until it got into grass and then it would start to bog down and wouldnt recover until he backed out of the grass. He tore it apart and finally found that the choke was binding up and the choke plate was partially shutting the engine down because it was not opening all all the way. He said that the choke was a twisted bimetal spring that attached to the muffler and as the muffler gets hot so does the choke spring and it was supposed to uncoil (because of the heat) and keep the choke open. But because it was binding the choke would stay partially shut. He tore it apart figured out what was binding, fixed it and all is good now.

Of course I dont know if you have the same engine.

 

[Geo-TH,In]

Try the usual things.
Start with spark plug.
Dump out gas , use fresh.
If you have grass and dirt inside tank, flush tank.
Then take carb apart and look for crap.

 

[kencombs]

If it has a primer bulb check it for cracks

 

[DoubleO7]

If there is a rubber or plastic fuel line, check it for softness.
E10 might have ruined the line inside.

 

[CBBC]

Id look at the fuel line, filter and into the carb bowl... could be a jet plugged or float stuck but sun times something much simpler like a pinched hose.

My neighbour with a small woodmizer sawmill had asked me to help him change the drive belt and a couple other things.
I got the belt switched and he was going to put the guards back together after he adjusted the tension. I left. It was running well even under load.

He called me a day later saying he had this 12 birtch that he cut half way through the log and the motor stopped. After it sat for a bit it would run again. The clear fuel filter had some fuel in it... normal to what I had seen. We put some gas through the top of the carb and it ran fine so not a spark. There is an electric fuel shut of in the bottom of those Koehler carbs and I thought maybe it was sticking or plugged with sawdust.
Almost going to start taking things apart but first I reached up to check if there was fuel in the external tank ( on top of carriage so gravity feed) as I looked down from the tank at the fuel hose to see if there was a shut off. There wasnt but the fuel line passed along the top of the saw blade guard and then into the motor. Except that one of the clamps holding the hose in place was missing right where the tensioner belt guard was.
He had pinched the hose when putting it back together. Just enough fuel to run, not enough to cut.
So always look for pinched or cracked fuel lines before getting to far into them. Ive had this problem on outboard motors too where there is an old leaky hose or poor tank connection.

Good luck.