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Kawasaki FH721 running bad

Discussion in 'Mechanic and Repair' started by Tact, Jul 29, 2011.

  1. Tact

    Tact LawnSite Member
    Posts: 11

    I have a Cub Cadet with a 25hp Kawasaki FV721V engine. This machine has never given me any major issues since I've owned it for five years. It has approx 125 hrs on it.

    Recently, when I cut thicker grass the engine bogs down and stutters so bad that it almost shuts down completely. I have to back up to take the load off and the engine has to catch up to relieve itself. It also started to do this when I made hard turns in the yard. Any kind of load makes the engine want to stall. Even sometime when going up a hill.

    I was thinking it might be a bad coil?? Can someone explain how to test the coil and what the readings should be??

    I changed the in-line fuel filter and blew out the air filter but was no help.

    Any suggestions would be greatly appreciated.
     
  2. steve4mc

    steve4mc LawnSite Member
    Posts: 22

    Tact:
    Since the point of the coil is to produce a spark at the spark plug, have you checked that you are getting fire to both plugs. Pull the plugs one at a time and put it back in the spark plug boot and hold against a ground (away from the plug hole) and check for spark when you crank it. I always like to hold mine with insulated pliers in case there is a crack in the insulation on the plug wire. If you are not getting spark on one side, then we may need to assume it is a coil. You could then swap coils from one side to the other to see if it follows.

    If you have spark on both sides then we go from there down other paths.
     
  3. Tact

    Tact LawnSite Member
    Posts: 11

    The engine runs fine and performs well until it warms up. That is when it starts to run poorly under a load. So I assume both coils are performing well at the beginning, but one, if not both, start to break down under a load.

    Can just testing the coils with a voltage/ohms meter tell me the condition of the coil, or does the coil have to be warmed up, then pulled and tested??

    Can someone explain the proceedure in testing a coil and what setting the voltage/ohms meter should be set at?
     
  4. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

    As I recall, Kaw has a CDI ohms test in their service manual but I'm not accustomed to scanning and sending info. If you do a search of the site you can likely find the stuff that The Rob has posted on that subject.

    Even then, an ohms test is not necessarily vaiid as it may test OK when cold and break down when it warms up. I keep two inline spark testers and when this dilemma comes up, I put them on the machine, start it up and set out in the sun to run. Listen and observe.
     
  5. Tact

    Tact LawnSite Member
    Posts: 11

    I guess I need a couple of inline testers, but I don't have any. Might see if Autozone has any.

    I tried to do a search, but came up with nothing. Maybe I'm searching with the wrong wording??
     
  6. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

    Try NAPA ----part number 7-05950. If they don't have one in stock, they still show they are available in their 2010 Outdoor Power Equipment catalog. Last I remember they were about 11.00 each.
     
  7. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

  8. Tact

    Tact LawnSite Member
    Posts: 11

    I took it to a local mechanic today and described my problem, stating that this mower was bogging down and spitting an sputtering in taller grass. He thought it might just be as simple as sharpening the blades as they appeared to be somewhat dull.

    So I let him sharpen the blades, got it home and it is doing the same thing, even in shorter grass. Pushing the levers forward, which puts it in a load situation, this thing just bogs down, almost dieing, but catches it's breath and mows a little further then starts the same thing over and over.

    Now I'm thinking it could be a fuel issue. Can the fuel pump on these be bypassed. I think not since the fuel lines are on top of the tanks and joined together with a T.

    Any more thoughts besides a possible coil issue???
     
  9. whosedog

    whosedog LawnSite Senior Member
    Posts: 730

    I'm having the same problem on my Wright Stander's 25 HP kawi FH721-v.It only bogs down when it's been running for an hour or more and only when the blades are on.So far I changed the plug,put a new fuel and oil filter and air filter on and changed the fuel pump(only cost $30,used a brigs fuel pump same as Kawi at 1/2 the cost).I sprayed the carb inside and all the linkage on the outside with carb cleaner.If that doesn't fix it, I may take it to the mechanic.Mine has 550 hours on it;I'm thinking replace the carb? Hydro pumps are working good just the engine sputters when under a load.
     
  10. Tact

    Tact LawnSite Member
    Posts: 11

    Mine mainly bogs down while cutting thicker grass. My grass is zoysia and it is thick, but I've never had loss of power like I'm experiencing. The engine runs fine either idling with blades engaged or not. It even runs fine at high rpm. It just bogs down horribly when cutting thicker grass to the point that it almost stalls out completely. :cry:

    If it was a coil problem, would it run so good when idling or at high rpms with the blades engaged while standing still?? This has got my head spinning at it only has about 160 hrs on it.
     
    Last edited: Jul 31, 2011

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