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Honda Engine quits in the same spot every week. What is going on?

Discussion in 'Lawn Mowing' started by MJB, Jun 8, 2011.

  1. MJB

    MJB LawnSite Silver Member
    from Wa
    Posts: 2,869

    OK all you mad scientist / mechanics heres my dilema. My little Honda walk behind will be running fine, I stop and fill it with gas from the same can it was running fine from and it won't start. It only happens on this property which happens to be a medical clinic with a MRI Trailer with giant magnets which we mow next to for about 10 minutes. What is this doing to my mower. It will sputter and barely idle, then die. Every week in the same spot. Now today it quit won't run at all or only sputters and dies. I've changed spark plugs and drained the fuel bowl no help. Did the magnetic field hurt the magneto?

    Any suggestions?
  2. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    The MRI only has a magnetic field when it's running. I would imagine the field would be strong enough to collapse the field in your magneto when it's running if you get close enough. Have you tried moving the mower away from the MRI and starting it?
  3. 44DCNF

    44DCNF LawnSite Bronze Member
    Posts: 1,460

    Correct me if I'm wrong, but don't fuel solenoids work on a magnetic principle-electicity being passed through a coil to operate a valve? How about oil level cut out switches? Does your honda have a fuel solenoid? It seems entirley possible that the field from a trailered MRI unit could disrupt small magnetic fields in the vicinity outside the trailer. This is why pumps and electromechanical devices are not allowed within the MRI suite. If an MRI can turn floor buffers and oxygen or helium cylinders into missiles, I too, imagine it could affect your mower. I have posed your question about mri trailers via an e-mail to an architect involved in the design, planning and construction of MRI suites and will report back with the answer if/when I receive it.
    Last edited: Jun 8, 2011
  4. txgrassguy

    txgrassguy LawnSite Gold Member
    Posts: 3,083

    First question, have you tried a different mower next to the MRI trailer?

    My crews and I have mowed next to MRI trailers for years with a myriad of different powered mowers and have yet to experience the problem you indicate.

    Could be a weakening coil/ignition system on your mower, particularly if it has a number of hours on it. The idea being with the weakened ignition system whatever field is being emitted by the trailer may distort the coil.
  5. MJB

    MJB LawnSite Silver Member
    from Wa
    Posts: 2,869

    Yes, Each time I get done with that section I refuel. Then when I try to start it away from the trailer it will start but barely idle then it dies. Usually after 5 minutes it clears up and runs fine the rest of the day. But today after an hr I got it running and it seemed fine. Shut it off and now it's back to sputtering and missing real bad. This mower is only a year old with very low hours.
  6. MJB

    MJB LawnSite Silver Member
    from Wa
    Posts: 2,869

    Not yet. I got it running long enough to finish that job. Now it won't run. You may be right about the coil. It doesn't effect it while it's running, only after I shut it down . I'm dropping it off at the dealer today.
  7. MJB

    MJB LawnSite Silver Member
    from Wa
    Posts: 2,869

    It's just a 21" self propelled walk behind lawn mower. The engine doesn't cut off while mowing at all. I'm thinking it acts like the coil is failing. This has happened 3 weeks in a row in the same spot. Only this week even after bringing it home it won't run right. So could that magnetic field effect the coil?
  8. jsf343

    jsf343 LawnSite Bronze Member
    Posts: 1,767

    scary. I think I would be more worried to what it could be doing to you or or health than the mower.

    Although the mower acting that way is very interesting. You may try calling Honda directly and talking witth them about it, I am pretty sure someone would have an answer, seems odd for sure. I would love to hear more on this one.
  9. 44DCNF

    44DCNF LawnSite Bronze Member
    Posts: 1,460

    Here is the reply I received from Mr. Gilk (who replied very promptly I might add).

    Thank You kindly, Mr. Gilk!

    I've highlighted an interesting point he also makes in the reverse as to how mowers may impact MRI's.

    "To the question...

    I read the thread online and this is intriguing...

    First, nearly all MRI scanners are 'always on' scanners. There are certain elements that only come on during the 'picture taking' process, but the magnetic field isn't one of them. The magnetic field remains on 24 / 7 for most MRIs (trailer-based MRI's are one of the rare exceptions where they may 'ramp it down' to move it, bringing it 'up to field' shortly after it's parked).

    Next, it's critical to realize that magnetism passes through everything that doesn't have magnetic properties (air, water, brick, concrete, non-magnetic metals, your body) as if it weren't there. This varies a bit depending on electrical conductivity of the object, but that's getting much more technical than we need at the moment.

    Physically large magnets (such as an MRI scanners), and very strong magnets (also such as MRI scanners) have magnetic fields that can reach some distance. Whereas the magnets that hold my daughter's artwork on the fridge door have zero measurable magnetic field by the time you're more than a few inches away, and MRI scanner's magnetic field is often measurable outside the scanner room.

    It is possible to shield a magnetic field, but this requires plates of steel. Because MRI trailers have to pass department of transportation weight restrictions, and the MRI's themselves weigh thousands and thousands of pounds (some up to about 25,000 pounds!), the trailers are largely made from aluminum, and the weight limits allow for little, if any, steel magnetic shielding.

    Magnetism doesn't harm people until you get obscenely high, but it can interact (dangerously) with medical devices, such as pacemakers and other types of implants. The FDA has set a threshold limit of 5 gauss (pronounced like 'mouse'), which is a measure of magnetic strength roughly equal to 10 times the Earth's magnetic field that makes compass needles point north, as the allowable limit to which unscreened individuals can be exposed. Anything higher than 5 gauss, and you're supposed to be checked for contraindications (such as implants) before you're allowed in.

    A lot would depend on what kind of MRI is inside that trailer, and what shielding (if any) is provided in the walls and floor of the trailer, to determine what the magnetic field strength is outside. It should be restricted outside the trailer to the 5 gauss bubble around the scanner... but that doesn't mean that it is.

    Now, while I know a lot about MRIs, I know squat about engines. I imagine that the magnetic field from the MRI could interfere with the solenoid of an engine, particularly since we know it can interact with other electronic / mechanical elements. I could also imagine that it might act differently on different mowers (particularly since I've not heard of this problem before). I have heard of mowers interfering with MRI scans (having a whirling steel blade near a precisely tuned magnet has disruptive effects when they're taking the pictures), but not the other way around.I hope that this answer is at least partially helpful. Please let me know what you learn about this, since now you've got my curiosity piqued!

    Tobias Gilk

    PS: if you're interested in seeing several examples of how powerful the attractive forces of MRI scanners are, check out the photo gallery at flying objects"
    Last edited: Jun 8, 2011
  10. MJB

    MJB LawnSite Silver Member
    from Wa
    Posts: 2,869

    Thanks for the info. This MRI trailer was brought in this spring. They put down grass on 1 side of it and blocked off the parking lot when in use on the other side. But no one said anything to us about mowing it each week. I string trim my wife mows. The grass goes right to the curb so we are maybe 18" from the trailer on the first few passes. Next week I'll take a picture of it.
    They said parking vehicles to close weakens their imaging. So if I come in before they do, I'm still exposed to the magnetic field it sounds like. Great !

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