lawnmower surging

[KJM]

Just finished mowing the lawn for (I hope) the last time this year. the lawn mower was constantly revving up and down. What would cause this? Some kind of carb problem I assume. Its a briggs and straton 3.5 hp push mower (I think)

 

[JASinIL2006]

Ours will do that if the air filter is getting clogged.

 

[KJM]

OK i'll check that. thanks

 

[tpenfield]

Surging is usually (not always) caused by the carburetor jet(s) becoming clogged. It causes a lean running condition and the governor on the engine (which most power equipment engines have) constantly is searching to adjust.

you can sort of test this out if you have a choke on the engine . . . give it a little bit of choke and see if it stops surging. If so, then run a high concentration of carburetor (or fuel injector) cleaner to the gas and run for a bit. Of course that may be something for next season.

 

[dpoff]

I had that problem and it was a rubber diaphram between the carb and gas tank. Easy fix. Lowes had them in stock. cheap part.

 

[Sprig]

Suggest cleaning the air filter(most of us totally forget to do that) and then run a little carb cleaner thru the carb. Also if you don't drain the little tank for winter then fill it to to top and add a little fuel stabilizer.

 

[WIMUSKY]

Briggs? There's your problem. You'll need to replace it with a Kohler and all will be well...... Lol Although, I am partial to Kohler. I put them through the paces...... One of the recommendations above should fix the issue.... I believe when my pusher did that it was the filter....

 

[KJM]

I'll try all these until I hit on the answer. thanks for the help

 

[Scott Danforth]

Either dirty air filter, or dirt in the carb plugging a jet

 

[robert graham]

That plastic carb fuel pick up tube that goes into the gas tank has a little screen in the bottom....it's plugged with debris....just clean it and your surging will stop

 

[Volphin]

Briggs? There's your problem. You'll need to replace it with a Kohler and all will be well...... Lol Although, I am partial to Kohler. I put them through the paces...... One of the recommendations above should fix the issue.... I believe when my pusher did that it was the filter....

LOL My 1992 Briggs 14.5 HP is still running strong. She sits outside all winter too. I change the oil once a season along with an air filter. I WISH it would die so I could get a new rider!

 

[bigdee]

Surging is usually (not always) caused by the carburetor jet(s) becoming clogged. It causes a lean running condition and the governor on the engine (which most power equipment engines have) constantly is searching to adjust.

you can sort of test this out if you have a choke on the engine . . . give it a little bit of choke and see if it stops surging. If so, then run a high concentration of carburetor (or fuel injector) cleaner to the gas and run for a bit. Of course that may be something for next season.

^^^X2^^^ Usually have to physically clean jet with small wire or compressed air. 10 minute job....remove bowl and its the big jet in bowl pickup.

 

[robert graham]

That plastic carb fuel pick up tube that goes into the gas tank has a little screen in the bottom....it's plugged with debris....just clean it and your surging will stop

Take it from me, this is your surging problem....clean that screen on the pick up tube....easy fix!...

 

[KJM]

I'm going to do all of the above

 

[dolluper]

As above diagram fuel pump between gas tank and carb the rest are guesses

 

[dolluper]

Did you fix or junk it eh!

 

[David Young]

I'd like to know how it went too . When my lawnmower had the idle surge, it was a dirty air filter. I have to clean mine 3-4 times per season. I had to rebuild the carb on my chainsaw last year and it was easy. After you've rebuild boat carbs, a small engine carburetor is a piece of cake

 

[gm280]

I'd like to know how it went too . When my lawnmower had the idle surge, it was a dirty air filter. I have to clean mine 3-4 times per season. I had to rebuild the carb on my chainsaw last year and it was easy. After you've rebuild boat carbs, a small engine carburetor is a piece of cake

Anybody that owns any yard equipment needs to know how to clean/rebuild carbs, or have tons of money for having them rebuilt. That is all part of owning such equipment. JMHO

 

[KJM]

I haven't done anything to fix it yet, too busy clearing snow this week! i'll probably leave it until the spring and then clean filters and carb. Hard to get motivated about a lawnmower in the winter.....I do appreciate the suggestions though, I'm saving them until I go at it.