I'm gonna bet on ignitor wire fire.  Here is an upgrade video on installing a larger fan and new ignitor on an older model.  The two big red wires coming from the new ignitor could have shorted, or perhaps the ignitor did not go off as programmed after starting   and that ignitor overheated and burned the insulation from the wires and thus a electrical fire. That would account for the fire coming out above or from the top of the fan, and why it went out shortly after turning off. Or perhaps the fan blades made contact with the red wires which were not positioned out of the way adequately. When the insulation was whacked off enough they shorted.  If so then it should be easy to diagnose by pulling the front panel off, then removing the fan (4 bolts), thus exposing the wires.
I have had a fan replacement experience with my GS because of noise and found that the fan blade was vibrating my hot rod wires, but fortunately had not cut them. I went ahead and re-routed the wires taking the slack out of them and went ahead with the new fan although probably could have left the old fan in. (warranty, so no cost to me).
Watch the You Tube below to see the proximity of those hot rod wires. 
https://www.youtube.com/watch?v=8FrlhE_6TTU

depending on how high he cranked up the grill temp I'm suspecting a grease fire.  Other than FEC PG500 and PG1000, I have not seen a grill that you can go from low heat to high heat on a long cook without causing a grease fire.

depending on how high he cranked up the grill temp I'm suspecting a grease fire.  Other than FEC PG500 and PG1000, I have not seen a grill that you can go from low heat to high heat on a long cook without causing a grease fire.

He was at low temp 230 doing brisket and went outside to go up to 240.  So no high temp.  And the flames went out several seconds after he pulled the plug. You may be correct, but he did not report flames inside when he pulled the brisket. We should find out more today.

depending on how high he cranked up the grill temp I'm suspecting a grease fire.  Other than FEC PG500 and PG1000, I have not seen a grill that you can go from low heat to high heat on a long cook without causing a grease fire.

He was at low temp 230 doing brisket and went outside to go up to 240.  So no high temp.  And the flames went out several seconds after he pulled the plug. You may be correct, but he did not report flames inside when he pulled the brisket. We should find out more today.

More info to come, but I think I solved it.

It’s running right now, so no electrical seems to be a cause. I took front panel off and inspected wires, auger housing, control housing...no sign of burning anywhere, only heat damage where flames were originating from.

I’ve got it set to 350 right now and will let that run for a bit to stabilize, then I’ll post some pics today.

No grease fire.


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Encouraging.

Thanks for everyone's questions, comments and thoughts. I've already emailed the manufacturer (SnH Grills owner) with my thoughts and pics.

After removing front panel to inspect and looking at wires, auger housing, controller housing, and not seeing any visible wire damage, only heat discoloration, I believe this was the start of an auger fire.

I was cooking low temp for a long time yesterday. The fan did not blow out the ash in the burn pot and it piled up (it was always on, but only ran low to medium front what I could tell, and not on high very often).

The ash piled up high enough over time to back up the pellets on the pellet slide/ramp where they started to burn. Flames started shooting out where the ramp meets the end of the auger tube, and the fan was strong enough to force enough air pressure to push flames out of this small gap. There is evidence of pellets that starting to burn in the auger, but they just smoldered out.

First pic, you can see the discoloration from the flames. This piece goes in front of the fan.
Second pic, no damage to wires going to fan (white) or the ignitor (red). (Edit: but you can see the discoloration on the auger tube from the flames).
3rd pic, uh-oh...the ash is clogging up the burn pot holes! But the red wires going to ignitor look OK.
4th pic, yep, the burn pot is full of ash, covering all the holes almost to the top! AND, you can see how it backed up creating a trail to the pellet slide/ramp that comes down from the auger tube!
5th pic...look at the pellet slide/shoot/ramp. It's got burnt pellets, AND you can see burnt pellets at the end of the auger way up top in the back.
6th pic, charred remains of pellets that I was able to sweep from the pellet slide/ramp with a toothbrush.
7th pic, I scraped off as much as I could off of that pellet slide.
8th pic...discoloration from the flames on the bottom of the auger tube that leads to the pellet ramp/slide.
9th pic...this is where I believe the flames were shooting out of...there is gap where the auger tube ends and meets the pellet ramp. This small opening allowed for forced air to push out the flames from lit pellets on the ramp leading to the auger. Once I cut power to the fan, the flames stopped. Pellets just smoldered out.

Everything ran just fine this morning at 350*. No flames shooting out, and the shutdown seemed to go ok.

Lesson: On long cooks at LOW temps (<230*) I need to be mindful of ash build up and take a moment to empty out the burn pot. Although I wanted this type of pellet drop system because I thought it reduced the likelihood of an auger burn back, it can happen (and I believe I've read a few posts of this happening to Memphis owners).

Oh, the ribs turned out great yesterday!

Something doesn't seem right.  I never had a problem with any grill (5 different ones) of having ash build up during the cook so much that it covered the air holes.  Either the fan is not working properly to move the ash out of the pot or the pellets are horrible and create a lot of ash or both.

Something doesn't seem right.  I never had a problem with any grill (5 different ones) of having ash build up during the cook so much that it covered the air holes.  Either the fan is not working properly to move the ash out of the pot or the pellets are horrible and create a lot of ash or both.

I know what caused it!   That violent rain storm you had the other night.  Blew into the hopper under the lid. Got the pellets wet.  That pile looks exactly what happens when you get moisture in the pellets.  Thats why they look like a bunch of unburned mush and why they clogged the fire pot.  When water gets into the hopper it does not spread uniformly, it just gets absorbed as it goes in.  Possible to have dry pellets in the bottom and wet pellets in the top. You may have added dry pellets during the cook, but the wet ones got in the slide before new drier ones did. Wet pellets swell and hold the moisture.If you did not empty the hopper this am.  Do so now! IMO Bet it does not happen again if you keep them dry. What do you think Bar Be Lew?

Hope you don't think I am pushy, if so I apologize. But two things of note:
1: I see you used aluminum foil to wrap the wires inside near the auger/slide and also at the external plug insertion. An electrician got all over me about that. It is possible to get a serious shock when the plug gets wet and you touch the aluminum foil or if a piece of the foil gets into the plug area.  Also around the wires, if there is any damage to the wires, you can get shocked or blow out your controls etc.
2: In picture #9-- I am concerned that there is a gap where the auger tube meets the slide tube. Pellets might escape or lodge in the opening.  Might also cause a build up to block the slide.  Am I seeing that gap correctly at the bottom of the auger tube?? Might be worth asking Dan (at SNH)about that.

PS great ribs. 

The Pelletfan members—

• Are willing to take the time to make a quality write-up of a pit or cook problem
• Are willing to diagnose it and offer a possible solution
• Never snipe at each other or display an "attitude"

It's not often the case elsewhere.

And, yes, RanrocSmoker, as you wrote, "To think, I was about to let this run all night!"  I cringe when I read about pits left unattended for long periods.

Something doesn't seem right.  I never had a problem with any grill (5 different ones) of having ash build up during the cook so much that it covered the air holes.  Either the fan is not working properly to move the ash out of the pot or the pellets are horrible and create a lot of ash or both.

I know what caused it!   That violent rain storm you had the other night.  Blew into the hopper under the lid. Got the pellets wet.  That pile looks exactly what happens when you get moisture in the pellets.  Thats why they look like a bunch of unburned mush and why they clogged the fire pot.  When water gets into the hopper it does not spread uniformly, it just gets absorbed as it goes in.  Possible to have dry pellets in the bottom and wet pellets in the top. You may have added dry pellets during the cook, but the wet ones got in the slide before new drier ones did. Wet pellets swell and hold the moisture.If you did not empty the hopper this am.  Do so now! IMO Bet it does not happen again if you keep them dry. What do you think Bar Be Lew?

I'm truly happy that so many people with a lot more experience can help diagnose what went on!!!

The pellets are Lumberjack 100% Pecan.

So....there were two nights of violent rain where the grill got soaked! the following days I would run my hand through the hopper to make sure that there wasn't any bridging, and it always felt dry.

BUT, I think you just solved another question I had.
Every time I emptied the ashes from the burn pot, I threw them (unlit) into my garden.
The next day, after a rain, it looked liked a pile of wet saw dust. A couple of times I thought to myself, hey I if I had a pellet press, I could probably make pellets out of that pile!

It never occurred to me that I was dumping out unburned pellets! You must be right about the pellets being moist!

Yesterday before the cook started, I looked in the hopper and except for maybe two or 3 pounds (hard to estimate), it was pretty empty. I dumped a fresh dry bag of pellets into the hopper before the cook (save for the 2 or so pounds I couldn't fit).

The old moistened pellets must've started the clumping in the burn pot at the start of the cook, leading to a chain of events that resulted in the fire. The pellets in there now are dry, as it did not rain yesterday. And I have the cover on it as well. Thanks for the insight!

Hope you don't think I am pushy, if so I apologize. But two things of note:
1: I see you used aluminum foil to wrap the wires inside near the auger/slide and also at the external plug insertion. An electrician got all over me about that. It is possible to get a serious shock when the plug gets wet and you touch the aluminum foil or if a piece of the foil gets into the plug area.  Also around the wires, if there is any damage to the wires, you can get shocked or blow out your controls etc.
2: In picture #9-- I am concerned that there is a gap where the auger tube meets the slide tube. Pellets might escape or lodge in the opening.  Might also cause a build up to block the slide.  Am I seeing that gap correctly at the bottom of the auger tube?? Might be worth asking Dan (at SNH)about that.

No need to apologize...I also started playing Pickleball, and just as with that, I am open to learning and suggestions!

Regarding your items:
1. Makes sense. I removed the foil. The wires didn't have any singe from the flames, and I think these are really high temp wires like for thermometer probes. They look like braided metal, but painted. I agree, they should be fine and I don't wanna risk getting shocked!
2. It's really hard to tell from the angle, but I do believe that the auger tube overlaps the pellet slide enough. The only thing that gets blown back has been pellet dust, but I've not seen any evidence of pellets (whole or in pieces) on the fan or around that area. But to your point, it doesn't seemed sealed at all.

The Pelletfan members—

• Are willing to take the time to make a quality write-up of a pit or cook problem
• Are willing to diagnose it and offer a possible solution
• Never snipe at each other or display an "attitude"

It's not often the case elsewhere.

And, yes, RanrocSmoker, as you wrote, "To think, I was about to let this run all night!"  I cringe when I read about pits left unattended for long periods.

This is an incredible site! I hope we all continue to add to the knowledge base as we are able to. It's so helpful for everyone.

(And Thank You Mr. Bentley for letting me join last year...I think my anniversary is coming up  )