Pulsing lawnmower

[Bruce Page]

My 3 year old Troy Bilt, Lowes special started a consistent RPM pulsing today; vroom, pause, vroom, pause.
Carburetion problem?

[Mac McQuinn]

I would first check the fuel tank's vented cap. Second I would use a non-Ethanol gas if available, I like the Rec90 fuel I buy from my local BP station.
Mac

[Bruce Page]

Ah! I didn't think of that!
Thanks

[Leo Graywacz]

Narrow the spark plug gap. That's what I did for my Snowblower that did the same thing.

[Lee Schierer]

Check the oil level it could be low. Also clean the air filter. Check for grass or debris on the automatic choke linkage.

[Phil Mueller]

You might also try putting a little Seaform gas stabilizer in the tank each use. It seems to fix almost anything.

[George Bokros]

Make sure you mix the Seafoam according to the directions on the can. Mix a gallon and just use it up in any small engine except for a two cycle which requires a different mix ratio.

Also it is a wise idea to Mac suggested use only non ethanol fuel. You can find some in your area on pure-gas.org

[Bruce Wrenn]

Forget the Seafoam, as it's a mixture of naptha, alcohol, and diesel fuel. Head over to Home Depot, and grab a bottle of "Mechanic in a Bottle." Not the fuel shield, but true "Mechanic in a Bottle." I don't know what's in this stuff, but local repair place that fixes commercial equipment turned me on to it. I have salvaged small engines from local dumpster that would not run without choke (your engine has an automatic choke) on. Following directions on bottle, add MIB, start engine, and after a few moments, it would smooth out. No connection to manufacturer, only VERY SATISFIED customer. Keep a couple bottles on hand. I add StarTron to fresh non alcohol gas when I purchase it.

[Stan Calow]

sometimes mine will do that when the spark plug cable is just a bit loose.

[Pat Barry]

Air filter is plugged.

[Dave Richards]

With all those things wrong with it, you might as well by a new one. :D

[Leo Graywacz]

With all those things wrong with it, you might as well by a new one. :D

I was thinking the same thing. LOL

[Rick Christopherson]

It's the governor. Clean the linkage pivots or put on a stronger spring.

[Leo Graywacz]

Thought the same thing on my snowblower and played with it forever. Gapped the spark plug smaller and it solved the issue.

[Rick Christopherson]

Thought the same thing on my snowblower and played with it forever. Gapped the spark plug smaller and it solved the issue.

No, you affected a symptom by decreasing the engine's performance, so the engine couldn't spool up as fast and cause over-rev. In other words, you slowed the engine's response to match the slow response of the governor, instead of speeding up the governor's response to match the engine.

[Leo Graywacz]

You'd think I'd notice the loss of power on a fully loaded snowblower. I didn't. It's possible that the plug had worn a bit and I just adjusted to to the proper gap also. The snow blower is 22 years old and has had 2 plug changes. I only changed it by .005

[Bruce Page]

With all those things wrong with it, you might as well by a new one. :D

Made me laugh!

I will start with the gas cap and go from there.
New air filter, oil change, links oiled, at start of the season. I don't expect that to be the problem but will check.

The vroom, pause, vroom, pause happened once before but smoothed itself out by the time I finished mowing. It did not recur until yesterday.

Thanks for the help!