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Kaw FH451V Surging @ low RPM?!?!

Discussion in 'Mechanic and Repair' started by twrnch, Jul 16, 2007.

  1. twrnch

    twrnch LawnSite Member
    Messages: 4

    Hi all, new to the forum and all searches have come up nil on this particlar problem. I have a Husqvarna Pro15 rider with the FH451V engine. At full throttle, the engine seems to run well, but when it is idled down, it surges as if it's starving for fuel. I changed the filter, no help. I have a suspicion that the pump is at fault. Do these pumps usually go bad slowly, as in only exhibiting problems at low RPMs when the vacuum is low, or should I be looking elsewhere? Any help would be appreciated before I just go out and buy a new pump. THanks- Great forum, lots of good info!
  2. Sydenstricker Landscaping

    Sydenstricker Landscaping LawnSite Bronze Member
    Messages: 1,281

    On my FH480V, it was doing the same, sounding like fuel starvation. I took the fuel bowl off and let some fuel drain out and make sure the float is clean and moves easily. Clean out the bottom of the float bowl, replace it, make sure you dont pinch that little o-ring gasket and you should be good to go. The least little bit of dirt can get in the carb jet, causing it to starve for fuel.
  3. gulfstreme

    gulfstreme LawnSite Member
    Messages: 83

    After some searches it looks like you may be the only one on the forum with one of these mowers.. could you give us a quick review? Thanks!
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Spray all ports/passages and jets out with carb & choke spray cleaner with the little straw, Sounds like you have a restriction in the carb. idle circuit, Also check the plug for being fouled after surging.
  5. twrnch

    twrnch LawnSite Member
    Messages: 4

    The Husqvarna Pro 15 is a swedish design mower. It is almost a zero turn, (around 4" turn radius), has 4 wheels and articulates like a front end loader in the center. The deck is in the front, mine has a 38" side discharge deck. The mower is also available with a 38" Rear disch., a 41" Rear/ Mulch deck called a Bioclip deck. My unit is equipped with the Kaw 15hp engine, although I am also told they came with Briggs and Kohler. The reason I purchased it was for use in my personal yard as it is relatively small, and has a lot of trees. Plus, the turf is somewhat weak and I was worried it would not stand up to the turns that a zero-turn makes (with the wheels pivoting). It's a good little mower, and fits my application perfectly. The only drawback is that there aren't a lot of them here in the US and therefore parts and information are hard to come by. Anyways, thanks guys for the help, I will clean out the bowl tonight, maybe spray some cleaner up into the jets. See if that helps-
  6. twrnch

    twrnch LawnSite Member
    Messages: 4

    Alright guys- cleaned out the carb good- took it off, washed everything in the parts washer, got all the jets out and sprayed them, sprayed through all the passages- looked brand new inside and out. Replaced it, put everything back together, started it up and did the same thing, in fact, it's worse. It used to run smooth at higher RPMs, but only surge at low rpm. Now it does it all the time. It's not too bad at high rpms, but still does it. As a point of curiosity though, I left the fan cover off, and just held the throttle linkage in place, and it ran fine (as long as I held the throttle in position). It seems as if something is going on with the feedback system to the carb (that connection between the throttle linkage and the crankcase). I don't know much about the linkage, or what all it is attached to, so I am really stumped. If anyone has any ideas, I would really like to hear them- thanks-
  7. morturf

    morturf LawnSite Senior Member
    from midwest
    Messages: 476

    Did you try running the engine without the air filter on? Not mowing with it like that.....just running the engine. We had a problem similar to this and it was solved by replacing the Kawi air filter with an after-market one from Oregon. If the engine is running well without the filter on...try a different air filter. Worked like a charm for us.
  8. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    That's a good question, "Fixed" jet carbs are jetted to run properly with the air filter on.

    Also, I wouldn't run a engine more than a minute or two with the flywheel cover off. They heat up quick other wise.
  9. twrnch

    twrnch LawnSite Member
    Messages: 4

    Hey all- have a serious case of "foot-in-mouth" disease this morning. After my knee-jerk post last night following the failed carb cleaning, I did another search here and found some things about running the engine with half choke. Tried that and it purred like a kitten... i.e. I didn't get all the crud out of the carb :hammerhead: . Took it apart again, shot some more stuff through the jets, put it back on- now it runs great....:rolleyes: Anyways, thanks for all the help here guys- great forum, lots to learn and lots of good people to help. Just gotta change the oil and this thing will be good to go-

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