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  1. #1
    Silver Member
    Join Date
    Feb 2001
    Posts
    149
    Location
    South of Kansas City
    Tractor
    JD4400HST

    Default Toro Z589 Fuel Problem--help

    This Toro Z589 has a water-cooled, digital fuel-injected Kawasaki engine and started having fuel problems at 52 hours in which the fuel pump heats up and it runs out of fuel in the fuel filter OR it runs out of fuel in the fuel filter and then the fuel pump heats up -- in any event, the fuel filter empties and if the mower is turned off and then to the on position, the fuel pump then fills the filter which immediately empties and the fuel is bubbling as if it were boiling. This happens after about 45 minutes of mowing. Let it sit for 10-15 minutes and it starts up and runs great for another 45 minutes or so and the whole fuel issue is repeated. Normally, when during the times when it is actually running right, the fuel pump is warm and not hot.

    The dealer cannot get to it for 2-3 weeks and then a week for parts means too much down time at this time of year, so I have been putting up with it. The dealer allowed me to install a new fuel tank selector valve and I coughed up the money for a new fuel pump ($171) and neither helped the situation. It does not make any difference which tank is used as the fuel source.

    Since the downtime at the dealer is such a killer, can anyone suggest what might be the solution to the fuel filter emptying after just 45 minutes of run time with so few hours on the mower -- after the fuel pump and selector valve have been replaced?

    Unless I can get this cleared up ASAP, it will be my first and LAST (allegedly "commercial") Toro ZMaster. GRRRRRRRRR

    Suggestions/opinions/experience?

    Mike_S

  2. #2
    Gold Member
    Join Date
    Jun 2007
    Posts
    425
    Location
    Northern West Virginia
    Tractor
    JD

    Default Re: Toro Z589 Fuel Problem--help

    Could it be that the vent that allows air into your fuel tank(s) is clogged?

    After running for 45 minutes, you may have used enough fuel to have gradually developed a vacuum in the tank (if air can't get in through the vent) which the fuel pump can't overcome, causing it to overheat and leave the filter empty. When you turn it off, the vacuum leaks off but the hot fuel pump is vaporizing the gas. When you let it sit, the pump cools off and then you're good to go for another 45 minutes.

    Since you say it doesn't matter which gas tank you're using, my theory assumes both tanks share the same vent, such as through pollution equipment installed to recover gas fumes.

    You could test this by simply mowing for about 40 minutes, then loosening or even removing the gas cap, and mowing for another 10 or 15 minutes on fairly level ground.

    A second possibility is that there is a restriction in the tubing from your gas tanks to the engine, perhaps at the point where the lines from the two gas tanks join. This would have the same effect as a plugged vent.

  3. #3
    Silver Member
    Join Date
    Feb 2001
    Posts
    149
    Location
    South of Kansas City
    Tractor
    JD4400HST

    Default Re: Toro Z589 Fuel Problem--help

    Quote Originally Posted by TedLaRue
    Could it be that the vent that allows air into your fuel tank(s) is clogged?

    After running for 45 minutes, you may have used enough fuel to have gradually developed a vacuum in the tank (if air can't get in through the vent) which the fuel pump can't overcome, causing it to overheat and leave the filter empty. When you turn it off, the vacuum leaks off but the hot fuel pump is vaporizing the gas. When you let it sit, the pump cools off and then you're good to go for another 45 minutes.

    Since you say it doesn't matter which gas tank you're using, my theory assumes both tanks share the same vent, such as through pollution equipment installed to recover gas fumes.

    You could test this by simply mowing for about 40 minutes, then loosening or even removing the gas cap, and mowing for another 10 or 15 minutes on fairly level ground.

    A second possibility is that there is a restriction in the tubing from your gas tanks to the engine, perhaps at the point where the lines from the two gas tanks join. This would have the same effect as a plugged vent.
    The gas tanks are totally separate and I have already done as you have suggested in regard to loosening the gas caps, and also checked for kinks in the fuel lines. Thanks for the suggestions, Ted.

    MikeSp

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