Can't figure out Atwood furnace no ignition

[Straylight]

Make and model: Atwood Hydroflame 8525-IV

Complaint: Furnace clicks but fails to ignite, then goes into lockout mode after three attempts. Control board has green light, turns to red during ignition attempt and then back to green after failure, then no light when in lockout.

Parts cannon so far:

• New control board (Dinosaur)
• New ignitor/flame sensor unit (OEM, with new high-voltage cable)
• New propane regulator

Interventions/checks so far:

• Battery voltage at ~12.7v, and furnace will not light on shore or generator power either.
• Removed and probed sail switch and found continuity between contacts when sail was depressed by hand (multimeter in continuity mode gave steady beep). Brushed sail switch contacts with wire brush and pencil eraser and reinstalled. No change.
• Blew out propane line with compressed air, propane tank is full, water heater is currently running on propane and stove has been used repeatedly; note that problem still occurs if water heater is off. Fridge is also running on propane without a hitch. I smell slight propane smell at furnace exhaust when it tries to ignite.
• Removed and cleaned burner chamber thing; minor rust and deterioration.

Any ideas as to what to check next?

[77rollalong]

when I was testing mine I used a bar-bq regulator and a 20lb tank and a car battery to run it without the case on

[Straylight]

I cleaned the burner orifice last time I was diagnosing: Took off the L-shaped connector between the valve and chamber, removed the pinhole orifice, soaked in alcohol, did some scrubbing with a few strands of stranded copper wire.

[dougrainer]

newman fulltimer wrote:
Have you cleaned the burner orphice? If not take it off carefully and soak in some alchohol

You need to do this. I thought from your previous post you had done this. Doug

[newman_fulltime]

Have you cleaned the burner orphice? If not take it off carefully and soak in some alchohol

[Straylight]

Double posting just to say: Ugh what a pain in the butt it is to have to take the whole **** thing apart so many times

[Straylight]

Alrighty, did some more work, no joy so far:

• Removed burner/valve/etc. assembly and observed spark electrode. In shaded daylight, couldn't see spark when I heard spark click. Separated electrode tips until they were about 3/16" apart. Thereafter observed strong blue spark at the very tip of the electrodes.
• Checked voltage at end of wire that goes to propane valve, used nearby screw for ground. Observed ~10.9 volts. OK?
• Checked continuity of each coil; multimeter read 41 on both coils in continuity mode.
• Reconnected propane, turned on propane at tank (I only have one tank), ran stove and turned on fridge with no issues and with strong flow. Turned thermostat to 90, turned on heat, still trying to ignite and not igniting (repeated sparking for a few seconds, then nothing, then two more tries before hitting lockout). Cycled through to lockout 4 times and no change.

The spark really did look better after I separated the prongs a bit (being careful not to bend the ceramic one, just the other one). I thought that might have been it, so I put it back together a little prematurely.

I might go back in to vacuum out the pipes and check the combustion chamber again, but nothing looked amiss. Will also re-check the propane hole.

[enblethen]

You should separate the wiring on the coils so you can check continuity one at a time. Then compare readings.

[A1RVTraveler]

Did you remove the propane orifice and look for a bug in it. A small bug will only allow some propane to pass but not enough to light. You will still get a propane smell. If you do this, also move the electrode gap from 1/8 inch to 3/16 inch.

[Straylight]

enblethen wrote:
While it is clicking check to see if there is voltage from circuit board to the gas valve.
Another is to verify that the two coils on the gas valve have continuity.

OK, so checking voltage across the closest coil's positive and ground wires, for the first thing, and then continuity across the positive of one coil to the ground of the other?

dougrainer wrote:
Your burner is either dirty or the spark electrode is not adjusted to spark between the burner and the electrode. Odds are the electrode is sparking to the top of the combustion chamber which will not ignite the LP. Doug

PS, from what you have done, you are qualified to be a Mobile RV tech

How do I adjust the spark electrode? The gap at the tip was 1/8" last I checked, which seems to be to spec? And thanks, I went to the University of I Own a Late-Nineties RV and I'm Kinda Broke. You'd be surprised how much you learn there!

77rollalong wrote:
try taking off the high voltage lead off where the burner is and placing it close to the metal frame and see if it sparks when it tries to light or not. Had mine do the same last week we had it out, it was a bad Neon (NE2) lamp near the High voltage coil fixed it …

Yikes, that seems a little spooky to test out. Would I hear the spark electrode clicking during ignition (as I do) if it wasn't sparking?

[stickdog]

Took a shower and water was hot as could be. Wife took a shower that evening and complained water was just so so. We were on 30 amp so HW was on gas. Knew we had plenty of gas as I had just filled No.! tank the day before and tank No.2 was full and only turned on hours before Tank 1 was filled. Turns out a bug had gotten into the HW heating tube and somehow shorted out the igniter on the HW tank. First time in 8 1/2 years full timing a bug got into HW or Furnace and caused problems.

[77rollalong]

if you are getting a bit of a smell of propane on the exhaust when it tries to start , gas valve should be ok, try taking off the high voltage lead off where the burner is and placing it close to the metal frame and see if it sparks when it tries to light or not. Had mine do the same last week we had it out, it was a bad Neon (NE2) lamp near the High voltage coil fixed it …

[dougrainer]

" I smell slight propane smell at furnace exhaust when it tries to ignite"

Bingo. Your burner is either dirty or the spark electrode is not adjusted to spark between the burner and the electrode. Odds are the electrode is sparking to the top of the combustion chamber which will not ignite the LP. Doug

PS, from what you have done, you are qualified to be a Mobile RV tech:B

[enblethen]

While it is clicking check to see if there is voltage from circuit board to the gas valve.
Another is to verify that the two coils on the gas valve have continuity.