Honda lawn mower surges at idle. The governor keeps pulsating which makes the idle pulsate. If you engage the blade and engage the chock, it runs fine. I checked and put in a new spark plug. The compression is about 60 psi. I notice just a fine spray of fuel coming back out of the carburetor. Any help would be appreciated.

The carburetor has two circuits, a main power circuit and an idle circuit. When the idle circuit gets partially clogged, the governor will drop the throttle shut, the engine partially dies and the governor yanks the throttle back open till the main kicks in. If the idle circuit gets completely clogged, the engine will need the choke partially on to make up for the missing air fuel mixture, will run rich and surge horribly. The carburetor needs to be cleaned out, a can of Berryman's spray can dissolve the crud out and restore operation. 90% of this problem is caused by old contaminated gas

"Govenor hunting" caused by a lean condition ,carb is starving for fuel ! Dirt in carb or water,or out of adjustment ,or leaking throttle shaft ....usually it is a plugged low idle passage,that causes this condition,and is almost impossible to remedy,but a good cleaning might help .....does it only governor hunt at low idle ? If so thats the issue !

wow seen a lot of these 20hp motors with rods broken

If the engine surges take a look at the governor spring. It sounds like the engine is reacting to load

Ron:

If the mower starts easily and runs well but surges, the problem is not your carburetor! There is an arm coming from the crank case that links to the carburetor throttle arm with a small rod (the rod has a spring around it). That is your throttle governor. Loosen the nut where the governor arm meets the shaft going into the crank case, set the throttle to full throttle and using a pliers, twist the governor arm (coming out of the crank case to full open (twisting the shaft in the same direction that the governor arm would twist it when you go to full throttle). Tighten the governor arm nut without changing that setting... don't let the governor arm move or let the governor arm shaft (coming out of the crank case ) move or the setting will be wrong. ( I know... a third hand would be useful to hold the governor arm to keep it from moving). You may have to make that adjustment a few time to get it right.

SOUNDS LIKE IT HAS A AIR LEAK SOME PLACE KIE THE GASGET OR THE INTAKE TUB MY BE CRACKED

This engine is air cooled anyway and cooled by the fan on the flywheel. The cowling is made in such a shape to help the flywheel fan move the air over the head fins. It sounds like that engine has the governor out of adjustment if it is pulsating or it may just have a carb gasket broken or even the throttle shaft worn (caused by the governor) in the carb. All these things work together for a smooth running engine. Be sure to check all these things not just one or two.

You have dirt and/or moisture in your carburetor float bowl. Remove the bowl, clean it out, remove the main jet and clean it out and you should be good to go

Please change your are filter,or clean it, I hope this helps you and thank you

When a small engine "surges" in all speed ranges the possible causes are:

*Dirty air filter

*Water or contamination in the fuel system.

*Breaks in the spark plug wire (leaking), loose or corroded terminal connections causing an intermittent failure.

*Misadjusted or malfunctioning governor.

Problems with surging only when under load or at idle are likely caused by carb blockage or misadjustment.

Hope this helped and good luck to ya!