Surgine is generally an indication that the mixture is too lean. You didn't give the engine model number but I think you will find that engine still has an idle mixture screw which needs to be turned counter clockwise an 8th of a turn or so.

Walt Conner

I would clean the carb. with carb. cleaner (read instructions on can) do as walt suggested adjust the carb. I would also think about removing the gas tank next time its empty and clean it out. While I had it I would inspect the rubber gas hose from the tank to the carb. especially if it tank is under the seat. I would look for dry rot, cracks, and chafed areas. All heck,, just replace it and it will be good for another 10 years.

Ive dealed with surging alot, its generaly caused by 3 things. A clogged carb, intake valve lash too tight, or the governer is set to sensitive (most unlikely). If you see the carb spitting then most likely it has to do with the valves.

I agree with Walt and rcmoser.
My moneys on a clogged tank or carb since I assume up until now it ran fine. Although not a tractor I had the same problem with a chipper. It came with our vacation place and had set with old gas for too long. In addition the gas tank had this plastic partition with a spunge-like thing inside that had of course degraded and clogged up everything. Replaced the carb and tank and no more problems. As an aside I am constantly humbled by the amount of knowledge on this forum.

I had the same problem this Spring since I forgot to shut the fuel shut-off valve and run the engine dry before Winter came. A can of carb cleaner had it running good as new.

i checked the owners manual. not sure about the engine # but here's the # in the engine owners manual-

model 28T707
type 1154E1
code 000301ZE

the tank is not under the seat it is under the hood in front of the steering wheel. i never cleaned it but i did replace the fuel lines (each side of the fuel filter) either last year or the year before.

in the fall i do put stabil in the gas so that the last 2 times i mow stabil is in the gas/carb. after the final mowing, i syphon out the gas then run the engine dry. i then disconnect the fuel line to drain any gas there but it has stabil in it just in case. i store the mower over the winter in the basement at 55 degrees so condensation should not be a problem.

how do i use the carb cleaner, do i have to take the carb off (which i don't feel qualified to do) or do you add it to the gas or spray it into the air intake?

thanks,

tom

The model number is helpful. The IPL shows an idle mixture screw. I think, however, that this engine is generally called a 12.5 hp not that it matters.

IF the adjustment screw does not help, you might try some SeaFoam in your fuel mixture for a tank or two if you don't want to tear the carb down.

Walt Conner

You say you replaced the fuel lines. Did you replace the filter also? (with the correct color, Red)

I feel like a broken record! ...

If your intake gaskets crack or shrink, it will cause surging, as mentioned above, it will be running lean, due to the extra raw air being sucked in. This can be detected by spraying the area of the gaskets with WD-40 or any other flammable spray, to see if the engine smooths out.

Maybe your engine is a neo-conservative? They are pro-surge ya know ;)

Asbestos suit is on, flame away.

you might try some SeaFoam in your fuel mixture for a tank or two if you don't want to tear the carb down.

i don't want to touch the carb, i'll try the local auto parts store or mower dealerships for SEA FOAM. if that is not available is there another product or 2 you'd suggest?

Did you replace the filter also? (with the correct color, Red)

RED? no it was a generic gas filter that looked exactly the same as the one i took off. this was from a mower/tractor dealer in town. you mean i need to use a B&S filter? i have used generic filters for years without any trouble.

tom

I'll second the sea foam in the gas. An aggressive treatment might be best.
Look for it in a boating store.
Ask a local dealer if they can stock it. Once people use it & see it work, they stay with it.
The claims on the can seem exaggerated especially as an oil treatment, which I haven't done, but as a decarb treatment & general fuel system cleaner I have with good success.
I know a pro small engine mechanic that often recommends it.

I actually had someone tell me to pour the Seafoam directly into the carb until the engine killed, then wait a few minutes and restart the engine. All I got was a garage full of white smoke (therefore I wouldn't suggest it). I have been using it as a gas mixture and plan on replacing Stabil with it once my current supply is gone (since it has gas stabilizer in it).

yesterday i discovered something. if i kept the choke 1/2 on for a few minutes then slowly pushed it in over the next 5 minutes it ran ok. seems it's too lean.

red gas filter? does that mean b&s all i ever used are generic filters.

thanks,

tom

Did you try the WD-40 trick?

There's only one thing that causes this...a dirty, partially clogged up carb. Take it apart and blow it out with carb cleaner and low pressure compressed air (25 lbs). If your careful, you can use the same gaskets, otherwise you'll have to buy (or make) new ones.

"There's only one thing that causes this...a dirty, partially clogged up carb"

Well that is not exactly so, that is one cause of lean mixture.

Walt Conner

My engine seems to surge while I am mowing, but not as noticeably while the engine is idling or if I am just stopped with the mower engaged. Is this something with the governor as mentioned here? Could the drive belt just be slipping?
I apologize if I diverted attention from the surge thread, but when I read this, it got me thinking.

Regarding the Sea Foam, I want to try it. I saw a bottle at an auto shop but it said it was oil treatment. Is that the same product mentioned here or is there another one meant for carb cleaning/fuel additive?

Thanks for correcting me, Walt. You're so right.I should have added that a bad gasket (or simply loose bolts) between the carb and block could be letting additional air into the mix. The fact that the surging lessens as the mower heats up would also indicate that a leaky gasket is present. The increased heat of the motor seals the gasket to some extent. Either way, it's in the carb's realm of operation.