Puzzling problems with engines just stopping

[davem1111 2,356]

I posted recently in another thread about having this problem with my 416-H but can't find what I wrote.  Basically, when I'm mowing with the 416-H, it runs great for 10-15 minutes, then it just dies. Sometimes it will start again after a few minutes of sitting, but I think what I determined (at least, one problem) is that the charging system isn't working so the battery goes dead, hence no spark. But it also seemed like the coil was getting very hot,  and it was a "non-standard" coil from what I could tell, so I bought a new coil and regulator. Installed those, tractor runs great, but still dies after mowing for a bit. I made sure the air filter isn't clogged, and fuel flow seems to be steady.  Yesterday I even tried putting a car battery on the left running board and hooking it up in parallel, and maybe that helped some but not enough. Tractor seems to sputter when going from forward to reverse with the PTO engaged, so maybe I have some faulty wiring with one or more safety switches?

 

Anyway, the plot thickens. 

 

While giving the 416-H some "cooling off" time, I started mowing with my GT-1848 (with Honda GX610 engine).  Guess what?   10-15 minutes and it died also. After a few times of that happening, I took it in the garage during a short spurt of running. Recently got some new parts for it so I changed the air filter (it was pretty bad). Due for oil & filter changes for engine and trans but didn't do that yet. Checked wiring, etc., nothing out of place. Battery fine, not run down.  WTH?  It was showing some bubbles in the fuel filter while running, so maybe something going on there? I only had time to run it again for a few minutes but I'm assuming that the problem isn't "solved".

 

It's been very hot, but I haven't had problems like this in the past with it just being hot outside.  I need to take the time to diagnose the charging system on the 416-H but am not anxious to tear into the stator, if that's where the problem is. Will do that if I need to. I'm going to be short on time between now and Labor Day though. Still have about 1/3 of the yard unmowed, and it will be a foot tall before I can get to it assuming I have a tractor running long enough.  My 312-A is in pieces because I finally decided to clean that up and do some repainting.... bad timing.  4 decks, only 2 working right now. Sheesh. I need to retire. 

[ebinmaine 80,694]

Is vapor lock a possibility? 

@squonk mentioned a particular type of fuel filter that's more prone than others.  

[c-series don 12,444]

My first thought was plugged vent in the gas cap, causing vapor lock as Eric said. But with two tractors doing it, now I’m confused 🤔 

[squonk 48,119]

Let's see the fuel filter you're using.

[sqrlgtr 3,925]

EMP

An electromagnetic pulse (EMP) is a short, intense burst of energy. It can damage computers, power lines, and electronic devices. An EMP happens because of natural events like lightning or solar flares, or man-made events like high-altitude nuclear blasts. [1, 2, 3, 4, 5, 6]

I suggest a faraday cage while mowing.

 

[Bill D 3,156]

Any chance a mouse got into the engines.  If they overheat they will shut down.

[lynnmor 9,040]

I guess that the 416H has an Onan engine, if so the most likely cause of shutdown when hot is the ignition module next to the stator.  To test, have a spark plug ready and stick it on one of the spark plug wires and hold the threaded end against a metal engine part while cranking the engine.  Do this as quickly as possible after it shuts down and look for spark.  If none, wait till it cools and test again. Those ignition modules can get temperature sensitive with age.  Maybe your other tractor has the same issue.

[rmaynard 17,582]

Pure coincidence that both did it. My guess is what Don said, clogged gas cap vent. Loosen the cap and see how long it runs. If it works, try the GT as well. Stranger things have been known to happen.

[davem1111 2,356]

5 hours ago, ebinmaine said:

Is vapor lock a possibility? 

@squonk mentioned a particular type of fuel filter that's more prone than others.  

 

Possible.  

 

2 hours ago, Bill D said:

Any chance a mouse got into the engines.  If they overheat they will shut down.

 

On the Onan, more possible - it has more tins covering things.  The Honda engine could have something hiding in there though.

 

2 hours ago, lynnmor said:

I guess that the 416H has an Onan engine, if so the most likely cause of shutdown when hot is the ignition module next to the stator.  To test, have a spark plug ready and stick it on one of the spark plug wires and hold the threaded end against a metal engine part while cranking the engine.  Do this as quickly as possible after it shuts down and look for spark.  If none, wait till it cools and test again. Those ignition modules can get temperature sensitive with age.  Maybe your other tractor has the same issue.

 

Very interesting.  I need to rule out the fuel issues first, which will include draining tank, cleaning screen on outlet valve (or replacing), replacing all fuel line and filter. I have new line and filters already, maybe one tank outlet valve.  The fuel filter on the 416-H is very old and has black paint on it from a P.O. so I can't even see if fuel is moving through it, but.... this tractor ran fine until recently.  But it's been bloody hot lately.

 

As I mentioned, on the 416-H I recently replaced the coil, regulator, and condensor, but didn't know about the ignition module thingy. I bought those as a set, not this one because it includes the module and not the regulator:

 

I can probably do the ignition module test sometime soon, but getting under there to replace the module if it's bad will probably be a fall/winter project.  I don't know if the Honda engine has the equivalent device in a similar location, will have to investigate.

 

 

 

 

I'll see what happens if I can eliminate fuel and possibly mouse-related issues first.  If I need to pull the Honda engine to work on it, I was planning to do that this fall anyway. Whoever did the re-power thought it would be "cool" to mount the engine on a pair of pressure-treated 2x4's, which have since gotten soft and my engine moves when I engage the PTO. Guess I should be grateful it hasn't just fallen out.... 

 

Thanks everyone!

 

 

[ebinmaine 80,694]

1 hour ago, davem1111 said:

pressure-treated 2x4's,

 

Steel would obviously be ideal but even a harder wood species would be a viable quick short term fix. 

[Handy Don 17,474]

51 minutes ago, ebinmaine said:

a harder wood species would be a viable quick short term fix

MANY an early engine used hardwood frame and engine supports. Hickory, rock maple, and white oat are all available without too much effort. 

[lynnmor 9,040]

1 hour ago, davem1111 said:

 

I can probably do the ignition module test sometime soon, but getting under there to replace the module if it's bad will probably be a fall/winter project.  I don't know if the Honda engine has the equivalent device in a similar location, will have to investigate.

 

 

 

Since the problem is very likely heat related you will not have a valid test or fix if you wait.  The repair takes about 2 hours with the shroud being the most trouble.  The flywheel will need a puller, I made a simple plate with 4 holes to match the the threaded holes in the flywheel plus a tapped hole in the center.  I don't like to use the typical steering wheel puller but many do just that.  The flywheel bolt should be loosened about 1-1/2 to 2 turns and your puller will push against it.  When installing the flywheel make sure the surfaces are completely clean and then apply just a hint of rust preventative.  Torque the bolt to 55 lb ft.

[Handy Don 17,474]

2 minutes ago, lynnmor said:

I made a simple plate with 4 holes to match the the threaded holes in the flywheel plus a tapped hole in the center. 

I copied this idea from one of your earlier postings and it worked perfectly. I was almost disappointed that the flywheel came off so easily!

 

After removing the puller and going to remove the center bolt, be SURE you are ready to hold onto the flywheel!  It is heavy and awkward to handle!

[lynnmor 9,040]

1 minute ago, Handy Don said:

I copied this idea from one of your earlier postings and it worked perfectly. I was almost disappointed that the flywheel came off so easily!

 

After removing the puller and going to remove the center bolt, be SURE you are ready to hold onto the flywheel!  It is heavy and awkward to handle!

 

Thank you.

 

I should have mentioned in my post that raising the flywheel side of the tractor a few inches makes the work easier and safer.

[davem1111 2,356]

1 hour ago, ebinmaine said:

 

Steel would obviously be ideal but even a harder wood species would be a viable quick short term fix. 

 

31 minutes ago, Handy Don said:

MANY an early engine used hardwood frame and engine supports. Hickory, rock maple, and white oat are all available without too much effort. 

 

Interesting. Maybe if I didn't already have some square steel tube on hand, I would get some fresh hardwood to replace what is probably just pine.

 

25 minutes ago, lynnmor said:

Since the problem is very likely heat related you will not have a valid test or fix if you wait.  The repair takes about 2 hours with the shroud being the most trouble.  The flywheel will need a puller, I made a simple plate with 4 holes to match the the threaded holes in the flywheel plus a tapped hole in the center.  I don't like to use the typical steering wheel puller but many do just that.  The flywheel bolt should be loosened about 1-1/2 to 2 turns and your puller will push against it.  When installing the flywheel make sure the surfaces are completely clean and then apply just a hint of rust preventative.  Torque the bolt to 55 lb ft.

 

 

It may be too late already. Going on a road trip and by the time I get back, hopefully the major heat wave is over.  Maybe I'll just plan on replacing it either way.  But like I said, I think I'll attack the possible fuel supply problem first. Thanks!

 

[Bill D 3,156]

On 8/19/2026 at 9:29 PM, davem1111 said:

 

 

Interesting. Maybe if I didn't already have some square steel tube on hand, I would get some fresh hardwood to replace what is probably just pine.

 

 

It may be too late already. Going on a road trip and by the time I get back, hopefully the major heat wave is over.  Maybe I'll just plan on replacing it either way.  But like I said, I think I'll attack the possible fuel supply problem first. Thanks!

 

Are you coming out to the east coast again?

[davem1111 2,356]

On 8/26/2026 at 7:13 AM, Bill D said:

Are you coming out to the east coast again?

 

Bill, I was already on my way east when you posted this, and this is the first time I've logged in since I got back.  Yeah, we did the drive IN-->NJ (stayed with brother for a few days)-->Boston then did a few vacation-y stops on the way back home:  Albany, NY-->Geneva,NY--> Erie, PA --> IN.  Had great weather and lake view at the last 2 stops. In Albany we were in a hotel within view of the Hudson River.

 

On 8/19/2026 at 3:09 PM, rmaynard said:

Pure coincidence that both did it. My guess is what Don said, clogged gas cap vent. Loosen the cap and see how long it runs. If it works, try the GT as well. Stranger things have been known to happen.

 

This seemed to help with the GT, so far. It has a non-standard cap and has a screw plugging the middle air hole. Guess I should just take that out.  Gas cap loosening didn't seem to help the 416 but I haven't messed with it much.  Too bloody hot here - we've been having "real feels" of like 105* - 108*.  And now it's getting dark much earlier, dang it.  I'll have some time tomorrow, if I can stay cool enough. Going away Sunday-Monday so maybe next weekend will be serious tractor work. 

[Bill D 3,156]

Any updates on this?

[davem1111 2,356]

I greatly appreciate all the suggestions. 

 

The GT-1848 seems to be fine now, with the gas cap loosened. I'll probably buy a new cap soon.

 

The 416-H though, is a puzzling one.  I need to get my 312-A project out of the garage so I have room to bring that one in and work on it (and review the suggestions above).  Loose gas cap made no difference. Ambient temp going down from 90+ to 70 or so didn't help either.  It still dies after 10-15 minutes of mowing, either at maybe 3/4 throttle or full throttle.  Sometimes if I disengage the PTO quickly it will start running again, then die a few seconds later. Yesterday it was backfiring at that time also. The PTO safety switch is either disabled or has faulty wiring or switch, and there's no seat switch, but I'm suspecting something electrical may not be right. It just doesn't make sense that it would be anything other than the engine overheating at this point, but I'm probably missing something.  Oh, and it also doesn't seem to be draining the battery. After a while it will start right up again. Haven't tested the magneto yet.. 

 

[Somewhat unrelated]:

BTW, I'll be starting another thread with pictures and details, but for visibility I'm going to mention it here:   Wife and I are serious about moving next year, hopefully early in the year, and I need to do some serious downsizing.  I'm going to sell that 416-H as well as a 520-H project tractor with swept front end, custom motion pedal, and a Kohler Series II KT17 engine that I believe was recently rebuilt before I acquired it (PO had died...).  Several Decks, a 400/500 series frame with hydro rear which I had belt-tested a while back and think is in decent shape, hydraulic lift cylinder, some fender and hood tins, wheels, tires, steering wheel, and a bunch of misc. smaller parts.  I'm hoping someone who is within driving distance will buy the whole lot and come haul it off - I will make a very enticing deal on the lot. I don't care that much about the money, since having this stuff hang around is going to make it difficult to prep the property for sale between now and next spring. Anything I still have at some point will be going out by the road and/or to scrap.

Anyone interested, send me a PM.  Some small things I can sell separately and ship, large stuff I may sell separately but I don't want to hurt my chances at selling the whole lot either.

[Bill D 3,156]

Sounds like a wiring issue or the infamous ignition module failure.   Easy way to eliminate the tractor wiring is to run a jumper from the battery positive to the positive on the coil.  If it keeps running then it's an issue with the tractor wiring, if not then you need an ignition module.   How many hours?