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View Full Version : Honda Engine quits in the same spot every week. What is going on?


MJB
06-08-2011, 01:06 AM
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?

Richard Martin
06-08-2011, 04:43 AM
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?

44DCNF
06-08-2011, 09:21 AM
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.

txgrassguy
06-08-2011, 09:27 AM
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.

MJB
06-08-2011, 09:39 AM
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?

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.

MJB
06-08-2011, 09:45 AM
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.

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.

MJB
06-08-2011, 09:50 AM
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.

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?

jsf343
06-08-2011, 10:12 AM
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.

44DCNF
06-08-2011, 11:05 AM
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 (http://www.simplyphysics.com/flying_objects.html)"

MJB
06-08-2011, 11:19 AM
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 (http://www.simplyphysics.com/flying_objects.html)"

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 !

44DCNF
06-08-2011, 11:35 AM
I strongly doubt that your health is at risk, based on the information within the letter. Maybe they would be willing to give you a gauss reading of the area near the trailer that you mow in.

quoted from the letter:

"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."

"Magnetism doesn't harm people until you get obscenely high,......."

I too am interested in the comments you get from either the hospitals people, the dealer, or Honda.


Another though just occured to me....I wonder if it is temporarily magnetizing a critical part of the carburetor or elsewhere like a checkball, needle valve, etc. Could this cause the running/restart issue until the magnetic field that such part may have picked up has dissipated or been removed by the flywheel and magneto's own magnetic field?

Maybe RestroRob has some good input on this as well.

Richard Martin
06-08-2011, 12:12 PM
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).


Call me wrong. You learn something new every day. :)

rlitman
06-08-2011, 12:50 PM
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).

MRI machines are either permanent magnets (like the kind on your refrigerator) of a weight too massive for a trailer, or electromagnets, which require electrical currents so high that they can only work with superconductors (requiring cryogenic cooling of at least liquid nitrogen, but typically liquid helium as well), or sometimes a hybrid of the two. Because of the cryogenic bath required for the superconductors, you cannot have current flowing while in motion, and magnet startup is a big/expensive process, so once these trailers park, they'll stay put for a while.
The field strength is absolutely incredible in the center, but sure can reach out of a trailer. Bring a compass (you don't like) to confirm.
The field in the center must be perfectly aligned and tuned to work, and bringing something as small as a steel washer into the room can severely distort the image produced, so a steel trailer, or steel shielding would not be practical.

rwaters
06-08-2011, 03:33 PM
Another though just occured to me....I wonder if it is temporarily magnetizing a critical part of the carburetor or elsewhere like a checkball, needle valve, etc. Could this cause the running/restart issue until the magnetic field that such part may have picked up has dissipated or been removed by the flywheel and magneto's own magnetic field?

Maybe RestroRob has some good input on this as well.

Most new honda engines have plastic needles and aluminum Carburetor and flywheels I do not think aluminum can be magnetized but I am no expert in this. I also wanted to post to see what he finds. I somewhat expect it to be a coil though.

MJB
06-13-2011, 08:33 PM
Ok I got the mower back the coil was bad. This mower doen't even have 100 hrs on it, so don't know what caused it. Problem is I'm going to the same property tommorrow, should I stay 10 ft away from the MRI trailer, and just stringtrim up close, or what? Is 10ft even going to make a difference? The last 3 weeks I mowed by it the mower would not restart for a while, and not at all after the the 3rd time. So is this thing killing my coil slowly? I'm noticing my trimmer starts harder to, is it damaging the the coil little by little I'm not there very long trimming. Now I'm paranoid for my equipment. I parked my truck 30 ft away the last few times and noticed it's not starting as fast as normal, takes more revolutions before it starts it's fuel injected, I'm parking away from this thing from now on, no sense in risking it.

nobagger
06-13-2011, 08:43 PM
Alein's man alien's. :help:

Birdhunter1
06-13-2011, 09:59 PM
Your mower needs a tin foil hat, go down to the bar area in your home community and find a drunk that hangs out behind the bar till 4 am and he probably knows how to make one.