Honda mower engine surges/pulses?

smezMarch 11, 2007

I have 2 yr old residential. Can't remember the model but it has the composite deck and hydro drive. One model up from the Harmony, I believe. Great for 2 seasons, however, it now surges and will not idle at all. Runs fine under a load and will idle half decent with the blade engaged. You can see the governor arm moving fore and aft as it pulses/surges. Checked the plug and looks good (no soot or carbon buildup)drained the carb bowl and put in new gas. I run Stabil in the gas. Do I need to check the carb jets or is this an issue with the governor? As far as the idle, it has been like that since new. Also, how can you check the full throttle rpm? Thanks, Smez

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canguy(British Columbia)

Sounds like a dirty carb. The Honda fuel system needs to be squeaky clean for the engine to run properly. Is your gas fresh? I bet this is the first time your mower has been run this year.

    Bookmark   March 11, 2007 at 4:10PM
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Yeah, new gas with Stabil. I drained the carb bowl but did not take apart the carb. Is this difficult for the average Joe? Do you need to disassemble it or can you take off the bowl and get to it? Thanks in advance.

    Bookmark   March 11, 2007 at 5:35PM
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nevada_walrus(Boulder City)

2 years old, should be the OHC engine. The carbs are EZ but do need removing, your idle ciruit is probably the problem.

Trouble is the OHC carbs are a snake to R&R for the first timer.

    Bookmark   March 11, 2007 at 9:06PM
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You might check the carb/intake pipe bolts to make sure they haven't loosened any, resulting in a vacuum leak. Probably not it, but inexpensive to check.

    Bookmark   March 11, 2007 at 9:23PM
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Me and a friend both had this problem with our mower, they would only run on high speed and would pulse or surge at idle. Tried cleaning the carb but that didn't work, tried replacing all the gaskets, no improvement. Bought a new carb from Plano Power Equipment for a whopping $16, along with the governor spring and rod, spent about $31 total. Installed the new carb and it purrs like a kitten, idles, runs on any speed, just like new. I did also move the spring on the lower right that attaches to the governor lever from one hole to another. Seems the carb and associated linkage is very touchy, that's why I replaced the other parts but the carb may have had a clogged jet and I just didn't feel like messing with it so replacing it did the trick for me.

    Bookmark   April 1, 2010 at 9:53PM
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well i put new gas new factory carb new blades cleaned muffler new plug adjust valves rechecked blade aliment, new air filter. still surges so what now it is a honda harmony 2 .5 years old.

    Bookmark   July 10, 2011 at 8:09PM
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I'm right there with you. I replaced my carb, air filter and spark plug and got it to fire up. However, it's now surging.

I'm going to look at lawn_dude's advice and mess with the springs (wish i had bought new ones and saved some $ on shipping).

I'm also going to make sure my gas cap is venting properly.

I'm just glad fall/winter is here and that my grass has started to go dormant.

    Bookmark   November 3, 2011 at 4:20PM
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Is the blade turning on this model, Albert, or do you engage the blade after the motor is running. If you do, it's not uncommon for the motor to be unsteady without a load. How does it sound with the blade running?

    Bookmark   November 3, 2011 at 8:22PM
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rosemallow(z7 Md)

Baymee has the right answer. Many BBC units will hunt somewhat with it off.
As I have stated many times before you can screw in the idle stop and this will resolve a lot of issues.
Do not adjust the idle jet or you may break it.

    Bookmark   November 5, 2011 at 9:41AM
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