Foreman 450ES (TRX450FE) Dies When Hot - Honda Foreman Forums : Rubicon, Rincon, Rancher and Recon Forum
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post #1 of 5 (permalink) Old 10-04-2019, 10:30 PM Thread Starter
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Foreman 450ES (TRX450FE) Dies When Hot

I just bought a used 2003 Foreman ES. It ran like a champ on the short pre-buy test ride, and the first few short rides around my place, but began dying after 10-30 minutes of riding. Sometimes it's preceded by a backfire, sometimes not. Oil light does NOT illuminate until after the engine dies.

When it dies it'll crank all day long but won't start until it's been allowed to sit and cool for 30+ minutes. Then it cranks right back up, runs like a champ for 10-30 minutes, and dies again. Repeat.

So far I have:

1) Removed/cleaned carb
2) Replaced petcock assembly (fuel pick-up on the old one was corroded/trashed)
3) Cleaned out fuel tank to make sure there's no debris
4) Running fresh ethanol-free fuel

Some more details:

The cooling fan was wired to an on/off switch by the previous owners and doesn't run off the temperature. I just leave the fan on when the machine is running.
I've checked (but not yet replaced) the plug. Gap is good, the threads/spark element have black-ish residue and aren't burnt white like I'd expect with a lean carb.
Fuel cap vents well in both directions, there's no noticeable 'hiss' of air when removing the cap indicating a blocked vent line.
The air filter has a light oil film on it. I don't know if the previous owners oiled it, or if there's oil blowback through the carb.
The engine oil may be overserviced from the previous owner. It's about 1/8"-3/16" above the "full" line when checked cold.
It's got an in-line fuel filter that I haven't replaced yet, but doesn't appear to have any blockage (it's a clear filter)
The magnetic starter switch behind the battery doesn't appear to stay seated in the magnetic shock rubber thing it's sitting in (pictures attached). Not sure if this is related in any way.

Ideas from what I've read so far:
Replace the plug - on the to-do list.
Replace the fuel filter - on the to-do list.
Replace the CDI - I've heard they go bad and can open the ignition curcuit when hot, killing the engine.
Valve adjustment - Not sure how/why this would cause the problem, open to input.
Replace the oil pressure (or is it temperature) switch. I expect I'd get an oil pressure light before the engine dies if this was bad?

I'm open to whatever suggestions yall have and, if it involves mechanical adjustments (like the valves) a reference on how to do the task would be greatly appreciated.
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post #2 of 5 (permalink) Old 10-05-2019, 01:17 AM
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Feel the regulator under the right rear fender and see if it's warm after running a while and/or check the charging voltage,

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post #3 of 5 (permalink) Old 10-05-2019, 10:26 PM Thread Starter
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Originally Posted by toodeep View Post
.....and/or check the charging voltage,
Where should I hook the multimeter up for that, I assume I'd be looking for 14V or so?
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post #4 of 5 (permalink) Old 10-09-2019, 09:22 PM
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Though the vent appears open, I’d try cracking the gas cap when the machine quits, just to confirm.

A next step might be to see if there is still spark when the machine quits.

Freeze spray might also be helpful, cooling one suspect component at a time...

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post #5 of 5 (permalink) Old 10-10-2019, 03:29 PM
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I had to replace the oil temperature sensor and that fixed it. Exact same scenario, backfire and all. Now my dies when it idles for more than a couple minutes. 98 Honda Foreman S.
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